Check here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96377#c3
A kernel/gcc bug that we think only affects gatesgarth. We can either backport the fix or upgrade gcc from 10.2 to 10.3.
I just added it here not to be forgotten. I guess the solution is either to upgrade to gcc 10.3 or to patch the few lines in the kernel to build with gcc 10.2.
hardknott has 10.3 and gatesgarth is outside of maintenance now so this is obsolete.