A liquid damaged phone is usually a big headache, especially if it fell into a water basin. It should be properly decontaminated by removing its core, the mother/logic board, and after ultrasonic cleaning it, the damage can be tentatively assessed. It takes quite a bit of work even before the repair can actually begin.
I’ve seen phone boards that have been thrown into an ultrasonic bath as they were, without removing protective shields, which is a bit like expecting to clean oneself just by getting under the shower fully dressed, shoes and hat included. Maybe fun, but little efficient
Getting concerned about which parts needs to be replaced is a useless exercise, no phone is damaged exactly the same way as another and nobody can question what was found in your phone without looking at it under a microscope. I’d suggest to look into other more important details..will your data be retained after repair, what warranty is the lab supplying, how much do they charge, is it worth from an economic prospective ?