This has been happening for a while now (prior to 1.17), but I really only figured something was wrong once I put axolotls in my lake with a conduit. All the aquatic mobs in the lake (turtles, axolotls, fish, etc.) are constantly attracted to the conduit and never move from it. Maybe this isn't a bug, but it would be a wierd feature if intended. The attached image shows my axolotls swimming in place and a turtle swimming in circles. However, when testing this in an ocean, this did not occur. All of the aquatic mobs swam around freely.