Some new info...
on another forum an user made some tests.
STLink reports the same ID code 0x410 but reports 128k instead of 64k:
STM32 STLink connection data:
12:41:19 : ST-LINK SN :
12:41:19 : V2J27S6
12:41:19 : Connected via SWD.
12:41:19 : SWD Frequency = 4,0 MHz.
12:41:19 : Connection mode : Connect Under Reset.
12:41:19 : Debug in Low Power mode enabled.
12:41:19 : Device ID:0x410
12:41:19 : Device flash Size : 64KBytes
12:41:19 : Device family :STM32F10xx Medium-density
CS32 STLink connection data:
12:58:02 : ST-LINK SN :
12:58:02 : V2J27S6
12:58:02 : Connected via SWD.
12:58:02 : SWD Frequency = 4,0 MHz.
12:58:02 : Connection mode : Connect Under Reset.
12:58:02 : Debug in Low Power mode enabled.
12:58:02 : Device ID:0x410
12:58:02 : Device flash Size : 128KBytes
12:58:02 : Device family :STM32F10xx Medium-density
The Serial UART (embedded) bootloader seems to work.
Best regards.