I have worked in 3 companies and none of them had installed anything on the work laptop. One IT department tried to, but I ignored all their messages. I would probably be pissed if I have to give up the right to work with privacy.

I had formatted the laptop both while getting it and returning it. I had filevault on and I wouldn't have shared my password.

Modern MDM solutions use Apple Business Manager to automatically deploy the MDM after a system wipe. If you have a company owned Apple device, and the company has it enrolled in ABM, then you can wipe and filevault all you want, but the agent will still be reinstalled, and the file vault key escrowed.