I've seen a minor trope in the fandom where when Bucky returns and is brought back to Avengers tower, Tony feels a little neglected and/or replaced.
Basically its a look at Tony's insecurities which is only exacerbated by the fact that Tony is usually in a relationship with Steve and Steve is paying more time and care to Bucky.
I remeber this one fic specifically that im trying to find but all i remeber is that the description talks about how Bucky can call Natasha, Nat and Tony isnt allowed to do that. I also know Tony gets hurt in the fic too during an assemble fight.
So my two part search is for the fic I described above and just a general one for insecure Tony threatened by the reappearance of Bucky.
Edit: Specific fic found in comments, but other recs welcome!