industrial-foregoing-1.19.2-3.3.2.1-3
titanium-1.19.2-3.7.0-23
Patchouli-1.19.2-77

It appears that the sewer is not removing the xp orb entities from the world after it "collects" them. They just sit there and the sewer just keeps processing the same orbs until they despawn 5 minutes later. A single Bottle o' Enchanting tossed onto a Sewer with Teir2 addons will end up producing 100+ buckets of Essence.

While I did discover this in my custom modpack world when trying to use Mob Grinding Util's XP Tap to stream Fluid XP onto a Sewer to make more Essence (workaround for lack of a Fluid Dictionary Converter, essentially), I was able to easily reproduce my findings using a fresh Curse profile with just MC1.19.2/Forge and IF/Titanium/Patchouli installed.