Yes, the OP map shows 100% perfect coverage in my neighborhood for AT&T and that’s definitely wrong. I just moved here and I’m contemplating getting a new carrier because it’s nearly unusable for data.
See my comment history for thoughts on AT&T. Unless you're in one of their strong markets (Georgia?) or using taxpayer subsidized and prioritized service through Firstnet, they are the worst of the major carriers. It's no surprise DISH partnered with them after running spectrum hoarding scam for over a decade.