jstests/replsets/internal_sessions_reaping_retryable_writes.js tests session reaping logic by manually deleting config.system.session entries and expecting subsequent session reap jobs to observe its effect (e.g. here). The test uses a 2 node replica set and the default write concern of majority, which used to guarantee the local read used by the session reap would observe the deletes, but now that we replicate oplog entries separately from applying them, we aren't guaranteed that, which can lead to failures. The test should be fixed to wait for its deletes to apply on all nodes before continuing.