> Comparisons of datums of a collatable type like text must be immutable (just as all comparisons used for B-Tree index scans must be immutable), which implies that operating system collation rules must never change. Though rare, updates to operating system collation rules can cause these issues. More commonly, an inconsistency in the collation order between a master server and a standby server is implicated, possibly because the major operating system version in use is inconsistent
And in particular also see https://wiki.postgresql.org/wiki/Locale_data_changes, which shows that the step from Centos7 to Centos8 is one that causes this problem. You need to reindex all text/varchar indexes when you make that upgrade.