I just take my phone out and look at it. Most establishments won’t give a shit as long as you are still able to be productive. Being said, if its to the point where you are being called out for it, high chance it is impacting work performance. That or you have a really shit manager. I’ve gone through like 6 managers and none of them have ever cared if we occasionally looked at our phone as long as it wasn’t impacting the work environment. The only time they ever address it is when some idiot abuses it or lets it impact work performance. Then they do a workwide broadcast saying “hey remember headphones and phones during work are not allowed” but they then only punish the ones actually failing to get the job done/are actually a problem.

You could probably start taking more bathroom breaks but, that defo won’t gain you any brownie points if anyone else on the team is reliant on you and if noticed you’ll end up higher on the chopping block next time they are looking to hire someone else on, technically this is illegal in the US but, they just find another reason to terminate. If its a manager issue, then I guess just ride it out, those types of managers generally don’t last too long anyway. That or look elsewhere for employment because it sounds like you are in micromanagement hell