As noted elsewhere I migrated my personal Mastodon account to a new instance.
Under Customize > Post Signature, in the settings of my federated blog @paolo@journal.paoloamoroso.com I added the Mastodon handle of my personal account. This way replying to my blog’s toots from the Fediverse also mentions my Mastodon handle from which I can reply and interact.
This worked fine with the old Mastodon instance @amoroso@fosstodon.org but not the new one @amoroso@oldbytes.space.