Linkedin also finally seemed to have simplified their notification and privacy settings. When you register, take a look at the settings and disable most notifications and data use.
Also, don’t use their mobile app. Just use it in a browser (via a progressive web app (PWA)). It sometimes wants you to install its all but that is not needed.
I don’t like Linkedin (as perfectly explained by other above) but it is kind of the de facto in business connections. I also found an internship via linkedin.