i have gentoo-sources built with genkernel if that matters. here's the output.
lightning /home/mark # grep cgroup /proc/mounts
tmpfs /sys/fs/cgroup tmpfs ro,nosuid,nodev,noexec,size=4096k,nr_inodes=1024,mode=755,inode64 0 0
cgroup2 /sys/fs/cgroup/unified cgroup2 rw,nosuid,nodev,noexec,relatime ...