Link previews happen if you hold click on a link or choose it in the right click menu. By default it shows pretty much just the title of the page and a banner asking you to enable ai summaries.

It’s kinda annoying, but not because of the ai. And you can easily disable it

The Fediverse isn’t federated.

All those clients are ActivityPub, not say some Twitter, some Facebook, some Bluesky, etc.

How is that different?

Just make JSON5 the new official version and I would be ok