Novak Djokovic lost two very important matches to Zverev and Medvedev in 2021 yet the Serbian respecs both of them.
The relationship between Djokovic and Zverev and Djokovic and Medvedev has been evolving over time. With the German, it was always friendly and now it's with Medvedev again. Even so, all three are competitors and Zverev and Medvedev defeated Djokovic in two very important matches for him in 2021. The Russian denied the Serbian the calendar grand slam in New York while Zverev ousted him at the Olympics.
Speaking to L'Equipe, Djokovic touched upon both explaining why he likes tehm as players and persons:
"I don't like people who pretend to be perfect. Perfection doesn't exist. That's why I love Medvedev and Zverev. They are authentic and they admit their mistakes. We have a great friendship."
Djokovic has a fair point as neither Medvedev nor Zverev conform to the usual tennis rules. Both are unapologetically unspoken saying what's on their mind when it comes to their tennis or other matters. Djokovic is very similar and that's quite unusual in tennis where most players have a very calculated approach.
That was even more apparent in the era of Federer and Nadal who rarely made problematic comments taking a neutral stance pretty much on everything.