I assume syncing settings. Ghostery also has 'added functionalty' when you sign up but I have never seen an explicit mention of what it is (I haven't signed up to try to see it myself).
If it is indeed syncing it once again highlights the achilles of internet for me. In the past on DC I have mentioned online syncing of passwords is a bad idea and in today's everything is eventually hacked world I wouldn't do it, but signing up for ghostery syncing is, at the risk of getting flamed for saying it,
lazyGhostery Tries to Comply With GDPR, but Ends Up Violating GDPR in the Process