Last time this specific R_PPC_REL24 relocation failure was seen in Debian build logs was for 26.4.6-1 in https://buildd.debian.org/status/fetch.php?pkg=galera-4&arch=powerpc&ver=26.4.6-1&stamp=1604830153&raw=0.
It has not occurred since and didn't happen on the latest 26.4.16-2 either, which had extra UBSAN issues fixed via https://salsa.debian.org/mariadb-team/galera-4/-/commit/19f010d78a98d8c481b57de27b0b59cdad8b979d
