My last job was in an open plan office with a constant noise level of 70db, peaking into 80db several times an hour. After about a year of it I noticed that it was affecting me mentally in a really bad way.

I would get super irritated at people for small insignificant things, be as adversarial/hostile as possible and try to turn every discussion into an argument, I saw slights everywhere, and everyone was stupid.

Once I noticed and figured out it was the noise that made me go crazy I bought noise canceling headphones (Sony WH1000XM3), wore them every day all day either listening to nothing or calming rain (using the Rainy Mood app on iPhone).

After a few weeks I was completely back to my normal happy self. All the perceived slights disappeared, other people were smart and reasonable again, small things were small things easily forgiven and meetings went much smother.

It's absolutely wild how the noise of an open plan office can affect you mentally. I was not the only one going crazy from it, earlier, shortly after we moved to the open plan office one of my colleagues was let go for having gone crazy in much the same way (he was more exposed to upper management).