Updated our wiki from 1.30 to 1.31. Ran update.php, and rest of wiki seems to be working fine.
After this, when I run rebuildrecentchanges.php or rebuildall.php, these scripts wrongly mark all prior recent changes to "b" for bot. New recent changes are showing as non-bot, as they should. Confirmed in recentchanges table that they are marked as bot there, and when I run a query to change them from 1 to 0 the listing on special:recentchanges becomes right. I can recreate this consistently on our wiki.
We run rebuildall.php as a cron overnight, so I know this was not happening before the update. With the "b" the edits are hidden by default in the recent changes.
One unusual bit of setup we have is that all users are part of a group CCMDB_legit and we have some user rights set up around this. However, I have a sister wiki with the same group and users (but login protected), and it doesn't add the "b" to recent changes.
We run SMW 2.5.6, though I can't see how that would be related. Php version is 7.1.17, hosted on Dreamhost.