why does homebrew keep uninstalling?

I have been using the homebrew package manager for years without problems. Ever since I got a new M2 Macbook a few months ago, I have run into a headache where I lose access to my brew packages and to the brew tool itself, every so often. For example, yt-dlp is a utility I use regularly. But if I don't use it for a few weeks, I frequently get an error message it does not recognize yt-dlp as a known command. When I then try to "brew install yt-dlp" the system does not recognize brew as a known command. If I go to [brew.sh](http://brew.sh), I am able to easily reinstall the brew tool, re-add it to my path, and "brew install yt-dlp" after which I am back in action. This only takes a minute or so but it has happened multiple times and I don't understand why. The only thing possibly non-standard about my configuration is that I am using bash and not zsh as a shell. Apologies if this question has come up multiple times but I couldn't readily find an answer. Is there a way I can make sure brew and the packages it installs STAY installed?