Use ststm32 5.6.0 for now

platformio.ini

 # STM32F103RE
 #
 [env:STM32F103RE]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103RE
 build_flags   = !python Marlin/src/HAL/HAL_STM32F1/build_flags.py
 # STM32F103RC_fysetc
 #
 [env:STM32F103RC_fysetc]
-platform          = ststm32
+platform          = ststm32@5.6.0
 framework         = arduino
 board             = genericSTM32F103RC
 #board_build.core = maple
 # BigTree SKR Mini V1.1 / SKR mini E3 / SKR E3 DIP (STM32F103RCT6 ARM Cortex-M3)
 #
 [env:STM32F103RC_bigtree]
-platform          = ststm32
+platform          = ststm32@5.6.0
 framework         = arduino
 board             = genericSTM32F103RC
 platform_packages = tool-stm32duino
 monitor_speed     = 115200
 
 [env:STM32F103RC_bigtree_USB]
-platform          = ststm32
+platform          = ststm32@5.6.0
 framework         = arduino
 board             = genericSTM32F103RC
 platform_packages = tool-stm32duino
 # STM32F4 with STM32GENERIC
 #
 [env:STM32F4]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = disco_f407vg
 build_flags   = ${common.build_flags} -DUSE_STM32GENERIC -DSTM32GENERIC -DSTM32F4 -DMENU_USB_SERIAL -DMENU_SERIAL=SerialUSB
 # STM32F7 with STM32GENERIC
 #
 [env:STM32F7]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = remram_v1
 build_flags   = ${common.build_flags} -DUSE_STM32GENERIC -DSTM32GENERIC -DSTM32F7 -DMENU_USB_SERIAL -DMENU_SERIAL=SerialUSB
 # ARMED (STM32)
 #
 [env:ARMED]
-platform    = ststm32
+platform    = ststm32@5.6.0
 framework   = arduino
 board       = armed_v1
 build_flags = ${common.build_flags} -DUSBCON -DUSBD_VID=0x0483 '-DUSB_MANUFACTURER="Unknown"' '-DUSB_PRODUCT="ARMED_V1"' -DHAL_PCD_MODULE_ENABLED -DUSBD_USE_CDC -O2 -ffreestanding -fsigned-char -fno-move-loop-invariants -fno-strict-aliasing -std=gnu11 -std=gnu++11
 # Longer 3D board in Alfawise U20 (STM32F103VET6)
 #
 [env:STM32F103VE_longer]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103VE
 monitor_speed = 250000
 # MKS Robin (STM32F103ZET6)
 #
 [env:mks_robin]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103ZE
 extra_scripts = buildroot/share/PlatformIO/scripts/mks_robin.py
 # MKS ROBIN LITE/LITE2 (STM32F103RCT6)
 #
 [env:mks_robin_lite]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103RC
 extra_scripts = buildroot/share/PlatformIO/scripts/mks_robin_lite.py
 # MKS Robin Mini (STM32F103VET6)
 #
 [env:mks_robin_mini]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103VE
 extra_scripts = buildroot/share/PlatformIO/scripts/mks_robin_mini.py
 # MKS Robin Nano (STM32F103VET6)
 #
 [env:mks_robin_nano]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103VE
 extra_scripts = buildroot/share/PlatformIO/scripts/mks_robin_nano.py
 # JGAurora A5S A1 (STM32F103ZET6)
 #
 [env:jgaurora_a5s_a1]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103ZE
 extra_scripts = buildroot/share/PlatformIO/scripts/jgaurora_a5s_a1_with_bootloader.py
 # Shield - https://github.com/jmz52/Hardware
 #
 [env:STM32F407VE_black]
-platform = ststm32@5.4.3
-framework = arduino
-board = blackSTM32F407VET6
+platform      = ststm32@5.6.0
+framework     = arduino
+board         = blackSTM32F407VET6
 extra_scripts = pre:buildroot/share/PlatformIO/scripts/black_stm32f407vet6.py
-build_flags = ${common.build_flags}
+build_flags   = ${common.build_flags}
   -DSTM32F4 -DUSBCON -DUSBD_USE_CDC -DUSBD_VID=0x0483 -DUSB_PRODUCT=\"BLACK_F407VE\"
-lib_deps = ${common.lib_deps}
-lib_ignore = Adafruit NeoPixel, TMCStepper, SailfishLCD, SailfishRGB_LED, SlowSoftI2CMaster
-src_filter = ${common.default_src_filter} +<src/HAL/HAL_STM32>
+lib_deps      = ${common.lib_deps}
+lib_ignore    = Adafruit NeoPixel, TMCStepper, SailfishLCD, SailfishRGB_LED, SlowSoftI2CMaster
+src_filter    = ${common.default_src_filter} +<src/HAL/HAL_STM32>
 monitor_speed = 250000
 
 #
 # Bigtreetech SKR Pro (STM32F407ZGT6 ARM Cortex-M4)
 #
 [env:BIGTREE_SKR_PRO]
-platform = ststm32
-framework = arduino
-board = BigTree_SKR_Pro
+platform      = ststm32@5.6.0
+framework     = arduino
+board         = BigTree_SKR_Pro
 extra_scripts = pre:buildroot/share/PlatformIO/scripts/generic_create_variant.py
-build_flags = ${common.build_flags}
+build_flags   = ${common.build_flags}
   -DUSBCON -DUSBD_USE_CDC -DUSBD_VID=0x0483 -DUSB_PRODUCT=\"STM32F407ZG\"
   -DTARGET_STM32F4 -DSTM32F407_5ZX -DVECT_TAB_OFFSET=0x8000 -DHAVE_HWSERIAL6
-lib_deps =
+lib_deps      =
   U8glib-HAL=https://github.com/MarlinFirmware/U8glib-HAL/archive/bugfix.zip
   LiquidCrystal@1.3.4
   TMCStepper@>=0.5.0,<1.0.0
   Adafruit NeoPixel
   LiquidTWI2=https://github.com/lincomatic/LiquidTWI2/archive/master.zip
   Arduino-L6470=https://github.com/ameyer/Arduino-L6470/archive/dev.zip
-src_filter = ${common.default_src_filter} +<src/HAL/HAL_STM32>
+src_filter    = ${common.default_src_filter} +<src/HAL/HAL_STM32>
 monitor_speed = 250000
 
 #
 # BIGTREE_SKR_BTT002 (STM32F407VET6 ARM Cortex-M4)
 #
 [env:BIGTREE_BTT002]
-platform = ststm32
-framework = arduino
-board = BigTree_Btt002
+platform      = ststm32@5.6.0
+framework     = arduino
+board         = BigTree_Btt002
 extra_scripts = pre:buildroot/share/PlatformIO/scripts/generic_create_variant.py
-build_flags = ${common.build_flags}
+build_flags   = ${common.build_flags}
   -DUSBCON -DUSBD_USE_CDC -DUSBD_VID=0x0483 -DUSB_PRODUCT=\"STM32F407VE\"
   -DTARGET_STM32F4 -DSTM32F407_5VX -DVECT_TAB_OFFSET=0x8000
   -DHAVE_HWSERIAL2
   -DHAVE_HWSERIAL3
   -DPIN_SERIAL2_RX=PD_6
   -DPIN_SERIAL2_TX=PD_5
-lib_deps = ${common.lib_deps}
-lib_ignore = Adafruit NeoPixel, SailfishLCD, SailfishRGB_LED, SlowSoftI2CMaster
-src_filter = ${common.default_src_filter} +<src/HAL/HAL_STM32>
+lib_deps      = ${common.lib_deps}
+lib_ignore    = Adafruit NeoPixel, SailfishLCD, SailfishRGB_LED, SlowSoftI2CMaster
+src_filter    = ${common.default_src_filter} +<src/HAL/HAL_STM32>
 monitor_speed = 250000
 
 #
 # Malyan M200 (STM32F103CB)
 #
 [env:STM32F103CB_malyan]
-platform    = ststm32
+platform    = ststm32@5.6.0
 framework   = arduino
 board       = malyanM200
 build_flags = !python Marlin/src/HAL/HAL_STM32F1/build_flags.py -DMCU_STM32F103CB -D __STM32F1__=1 -std=c++1y -D MOTHERBOARD="BOARD_MALYAN_M200" -DSERIAL_USB -ffunction-sections -fdata-sections -Wl,--gc-sections
 # Chitu boards like Tronxy X5s (STM32F103ZET6)
 #
 [env:chitu_f103]
-platform      = ststm32
+platform      = ststm32@5.6.0
 framework     = arduino
 board         = genericSTM32F103ZE
 extra_scripts = buildroot/share/PlatformIO/scripts/chitu_crypt.py