Thanks for the answer and the confirmation.
You're right about it being the default on #Mastodon, but it can be changed now. mastodon.social now sends a simple referrer and where's the harm on a bigger platform with many different users?
Here's a nice explanation for why it could help adoption and help with the visibility of a platform like lemmy.wotld without making users unsafe:
https://shkspr.mobi/blog/2024/12/mastodon-now-sends-referer-headers-hurrah/