A good lawyer can probably make the case that the profiles you view if tracked is your data that you are allowed to see under GDPR. But claiming that knowing who views you is part of GDPR seems like a big stretch.

Better for them to focus on the companies that don't allow you to opt out of what should be considered optional tracking without paying them.

You have a right under the GDPR to get a copy of all data associated with you PII data. Not just your PII data, but every table where PII is a field, or is transitively joinable. If they can provide somebody else something with your name associated with it, they have to provide it to you

I also don't understand what principle they have behind the GDPR claim. On LinkedIn you have some control on the visibility of your profile, and most infomation can be hidden if you want to (?!)

Buy when others see your profile, feels to me not different from a public addressbook lookup.