One of my previous jobs required we updated our personal phones and ticked a box in a document every month so that the company chat app was "on a secure environment/device".

I normally keep my phone up to date, but my employer shouldn't be telling me what to do with my private phone. I removed the company chat app since I didn't want to comply with them controlling my personal devices.

After that they couldn't reach me after hours. Great. After about 6 months they allowed me to use the chat app on my private phone again without insight or control over it. It may sound petty, but I think it's an important distinction.