I'm going to assume that 4g works decently enough where you are at this point. Much the same thing happened during the 4g rollout - it was too sparse, the phone spent too many resources hunting for a 4g signal when 3g was right there. You end up with a less stable connection because it's constantly bouncing back and forth.

I think if you look up how to disable 5g on whatever phone you have (which is possible on any phone) and stick to 4g for now you'll find the performance is as good as ever - if not better, with some of the load from other users being pushed to 5g.

I worked for "a major phone company" when 4g was rolling out. It's unfortunate during this period, but I don't know how you prevent it. 5g will objectively be better for 99.9% of users at some point - it might not be now, but everyone has to sell a 5g phone to "future proof" and have another selling feature. I wish the companies would educate people a little more on the rollout but then you're basically telling them "this thing we're selling you isn't really ready yet". And I mean, if you live in a major city, it's working just fine... but not everybody does.