I noticed a very small funnel near one of the jets in the stairs at the shallow side. I removed the jets and plugged them. I think the pool "pro" that opened things up assumed they were active.

I noticed some depression in the bottom on one side which would happen if the jet was draining under the liner on that side.

I'm topping off, hopefully for the last time.

The joys of learning a "new to me" pool.