It’s those behind the fedilab app -> https://toot.fedilab.app/@apps/115572783993063223

Oh, on. The setting thing was what I understood from the discussion in the link, but I didn’t go very deep

Ok, clear, thank you.

So this has been implemented as a Lemmy feature for more than one year, and it’s default behavioiur a setting for the particular community

Mmh, that’s not an explanation: when I look at an hastag timeline in mastodon, I expect to see all the posts that federate with my server and contain the relevant hastag.

In this case I for sure see also posts that are federated, but, AFAIK, do not contain the hashtag. The only element is the name of the community