In my last job, this happened often and saying no was not considered acceptable/an option.

In my last job, this happened often and saying no was not considered acceptable/an option. When I tried to do so, I was told that I was "not a team player" and treated worse than I already was. There would also consistently be meetings held without me in which it would be decided that I was taking on extra work/my manager's projects were being dumped on me, with no input from me or anyone asking if I had the capacity. Not only that, but my manager would then dump her work in my lap with little to no training and expect me to just figure it out.

When I asked for help because I was completely overloaded, my manager could not care less and would make comments about how she was working way more hours/longer days than me, as if it was a competition. Just a couple of many examples of how toxic that environment was.