I would expect the Bitcoin-QT client to stay on my machine, not to have to reinstall it every time.
It “disappears” - probably Mac OS’ XProtect finds something it doesn’t like in it and silently removes it
To reproduce: Have Bitcoin Core copied into the /Applications and wait some days
0.21.x, downloaded from Bitcoin.org
Mac OS 12.2, Macbook pro 16, 2019 model
It doesn’t keep log files anymore unless you have it set on the console app. I am not sure when it does this virus check.