The version of Python which is provided with SageMath-9.2 is Python-3.8. In ticket #30184, some work was done to support Python 3.9, but the replacement of 3.8 by 3.9 will be done later in ticket #30589. When installing sagemath 9.2, any version of python between 3.6, 3.7, 3.8 and 3.9 available on the system will be chosen. But, so far, we must admit that the sagemath library was not tested so much with Python 3.9. So maybe it was too early to allow sagemath-9.2 to use python 3.9... Anyway, it is too late now.
As explained here, you can impose the version of python3 of your choice when compiling sagemath. I suggest you chose Python 3.8. On my machine, python3.8 is here:
$ which python3.8
/usr/bin/python3.8
So, to compile sagemath with the python3.8 at /usr/bin/python3.8, one does:
make configure
./configure --with-python=/usr/bin/python3.8
MAKE='make -j5' make
If you don't have python other than version 3.9, then compile sagemath with the python provided by sage (which is currently version 3.8.5 I think):
make configure
./configure --without-system-python3
MAKE='make -j5' make
