gdalinfo --version
GDAL 3.3.2, released 2021/09/01
I have successfully used an older GDAL version for COG2GRD. This was done on ubuntu 20.04.
I think the requirement should be updated to reflect this, as it is quite a pain to manage gdal versions if you are making use of ESA SNAP. Ubuntu 20.04 does not support GDAL 3.6.x and making an upgrade to 22.04, which supports GDAL 3.6.x, is not trivial.