[quote]
Nobody on Mastodon can insert advertising into your user interface except the server you are signed up with and logged into. By default, Mastodon does not include any functionality to display ads. Unless you use Threads, you will not see any ads from Threads.
[/quote]
The remote Threads server could easily insert advertising content as part of the message data, I would think.
I don't know how well that would work. It's waaaay above my pay grade.
But my understanding, anything would have to be based on your public profile/posts and maybe who you interact with there. Everything is routed thru your server so they don't even get an IP to match with your FB account (if you even have one)