That it is common, won’t say it’s normal to do. They can get full access to your device by such profiles. You better can use your own mobile provider to access the internet instead of the company WiFi. Even without a installed profile they can track all your internet traffic.

I’m pretty sure it’s illegal in the European Union, if your employer requires this they will need to provide the phone, laptop or tablet. Its also not allowed for employers to make you install an app on your personal phone for example.

Its even more not allowed to monitor network traffic, then you will be violating both employee rights and the GDPR.

Dutch source: https://www.everphone.com/nl/blog/scheiden-van-gegevens-bij-mobiele-telefoon-van-de-zaak/