arm-none-eabi-gcc compiler error: thumb-1 mode PLT generation not currently supported

Hello.

I'm trying to use arm-none-eabi-gcc (with several versions such as 10.3-2021.10) on windows to compile a dynamic library for ARM Cortex-M33; If I use compile option with -mcpu=cortex-m33, the build fails with an error "warning: thumb-1 mode PLT generation not currently supported collect2.exe: error: ld returned 1 exit status。".  

Here is an example of my compile and result:

arm-none-eabi-gcc.exe -fPIC -mthumb -mcpu=cortex-m33 -mfloat-abi=hard -mfpu=fpv5-sp-d16 -fPIC -shared -nostdlib -nostartfiles -fdata-sections -ffunction-sections -Og -g0 -o libexternal_qrcode.so

The result:

arm-none-eabi/bin/ld.exe: libexternal_qrcode.so: warning: thumb-1 mode PLT generation not currently supported collect2.exe: error: ld returned 1 exit status。

however, if I change compile option to -mcpu=cortex-m4, the buid succeeds. 

1. what's the reason for the compile error? 
2. Will the dynamic library that compile with -mcpu=cortex-m4 can work on Cortex-M33 platform.