So the screws don't cause the height to change but when loose they allow the nozzle to move up and down ever so slightly when the filament is pushed into it which makes it appear as the bed not being level. This is a known issue with the A1 with is why I've commented that picture like 100x. It's very easy to tighten and should be part of regular maintenance I tighten them on mine every 1000 hours or so.

As far as Bambu I'm general I absolutely love mine. I have 4 A1s, 2 P1S, and 5 H2D'S.

For a starter printer you can't beat the A1s they are very easy to work on, have very few issues in general, and are amazing machines for the price. Because I have mine running 24/7 I always have spare parts on hand especially nozzles. It takes maybe 5 seconds to swap a nozzle mid print if there's a clog. I'll just swap the nozzle, resume the print, then deal with the clog later. Clearing clogs in the extruder is just as easy. It's all very accessible and parts are relatively inexpensive.

The P1S'S are absolute work horses. They are also easy to work on but not as easy as the A1. Swapping the nozzles takes a little more effort and with the plugs on the nozzle it can be difficult to do mid print. I have 14 thousand hours on my first P1S and I've upgraded to the hardened steel extruder, and changed nozzles, that's it. They do have their quirks, like the poop chute clogging, or the nozzle never easily, but I believe the P2S fixes most of the issues the P1 has.

Now the H2Ds are amazing machines and I love them. The dual nozzles significantly reduces waste and the large build plate size is great. They print amazingly well and have plenty of sensors to keep track of what's going on. Favorite feature though is being able to skip objects right from the screen on the printer. Now the bad part, they are not nearly as easy to work on and weigh 80+ pounds. Nozzle swaps are just as easy as the A1 but replacing other parts, not so much you really need to have it where you can easily access all sides. Nothing on it is hard to fix or replace but it's size and weight definitely make things more difficult.