When incremental membership syncing is enabled, quits aren't synced to matrix, only parts and joins are. Enabling debug logging shows that the bridge doesn't even register quits. Since this worked fine with 1.34.0 and because the bridge isn't aware of quits I assume that there has been a regression in matrix-org-irc with the update from 1.2.1 to 1.3.0.
When incremental membership syncing is enabled, quits aren't synced to matrix, only parts and joins are. Enabling debug logging shows that the bridge doesn't even register quits. Since this worked fine with 1.34.0 and because the bridge isn't aware of quits I assume that there has been a regression in matrix-org-irc with the update from 1.2.1 to 1.3.0.