Has there been any districts/states/counties that have strictly forbid teachers from choosing to wear a mask?? I'm unaware of this but would find it terribly cruel.

At the start of the pandemic, there were hospitals that explicitly forbid doctors from wearing masks, going so far as to fire them. There was one just up I-5 from me which did just that.

When an idiot with authority decides to flex their bureaucratic muscles, the cruelty is the point.