Browser pages zooms without prompt

I use Firefox because Safari pages will often zoom without a prompt and it is very irritating. All of a sudden with the newest Firefox update 89.0, this has started happening and usually with a small mouse movement. No keyboard keys are touched. And using command + - does not reduce it. I read a 2019 comment to use command + 0, so I will try that next time. But what the heck is making Firefox all of a sudden do this irritating zooming? Thanks!