there was an old RHEL-7.4 and RHEL-7.5 issue and fix in
but you have a (somehow) more recent version, 389-ds-base-1.3.10.2-10.el7_9.x86_64 ( and one 389-ds-base-1.3.11.1-1.el7_9.x86_6 ) , so this should be fixed.
the issue could have been related to sub operations.
the logs provided do show a replica with a large and growing pending list, taking several seconds to parse (in double digits).
and in this particular replication agreement, the consumer's max CSN is higher than the local supplier's one, so the remote replica/consumer is flagged as "ignored"
then later in time some updates go through as the RUV in the R.A. have been updated by a better knowledgeable replica.
but this seems to repeat (strange)
I want to suggest deleting the changelog, and re-init that replica, but maybe Thierry or Pierre or William B. have a better suggestion.
M.