This is a very good answer. Another thing you might do is ask the same questions to each tech individually. Maybe both approaches.

Sounds like he needs to do a cylinder leakage test to determine why the compression is low. Most likely you have worn rings on cylinder 4. If so, it’s time for an engine rebuild or replacement. For a wild guess on price, I’d say $3000 or more.

If it was slipping it would set a code for that, you’d have a bunch of lights on the dash.