No, filing of taxes isn't a requirement and I wasn't asked for it. In fact, while I submitted a late tax return just in case I would be asked about it, I didn't actually print it out.
They were much more interested in seeing money coming into my account, which I was able to prove with over a dozen bank statements that I brought along, of which they were only interested in the ones from 2024.
Indeed, they are getting stricter and I do agree that things have become a lot more stringent since July 2024. Just that this process started almost a decade ago; in that people living in Thailand on visa exempt stamps started to be scrutinized, especially at some of the airports and Aranyaprathet / Ranong / some of the southern borders beginning maybe around 2013-15 and this intensified in the post-Covid period.
You heard wrong. Phuket is one of the worst entry points. Most of the land borders are OK but don't do same day in/outs (except with the help of an agency at specific borders such as Ban Laem).
They got a lot harder on people staying on endless visa exemptions/tourist visas etc years ago, that is, a couple of years before Covid (around 2017 or 2018).
Things have continued to tighten up further in more recent times. However, we've been hearing of the occasional denied entry since at least 2015 and this has only intensified over the past few years except during Covid when almost no one could come in of course, and immigration was more flexible towards those stuck here.