Charging port maybe loose

First thing to do is clean the port. Charging ports are notorious for collecting lint and pocket debris, and once you get enough packed in there your cable can't seat correctly any longer. It may be harder to get out than you think; check this thread on Reddit for people who were having the same sort of issue.

Any way to fix USB port on Pixel 7A? Already tried cleaning out debris. : r/GooglePixel

If that doesn't work, the usual fix is to replace the charging port. Unfortunately, on your phone it's mounted on the motherboard unlike the majority of Android phones that have it on a separate daughter card that's cheap and easy to replace. The port itself doesn't cost much - a quick search showed them being sold on eBay for $2.75 USD, but the problem is the pin layout; it's made such that it can only be removed and replaced with a hot air station; can't be done with a soldering iron.

For a reputable repair shop it would be a simple operation; you might even be able to save money by pulling the logic board yourself and taking it in. This guide shows you how.

Google Pixel 7a Logic Board Replacement - iFixit Repair Guide

If you get it figured out, be sure to come back and let us know what you find; it's a common enough problem that people will appreciate knowing whatever you discover.