Summary
Kalaitzakis was the last pick in the 2021 draft, and was a surprising selection there (he was not even included on Sam Vecenie's top-100 board going into the draft). Despite showing some flashes of intrigue as a slashing wing, he hardly played in Europe and nothing pops statistically from his performance.

Kalaitzakis' appearance on the roster was as much about the luxury tax savings for a second round pick as anything else, and he ended up getting waived in order to allow the Bucks to sign Wes Matthews.
 
Cap Considerations
Kalaitzakis was waived by the Bucks in December, and has yet to sign with another NBA team. Teams will have multiple ways to sign Kalaitzakis as even teams without cap space could possibly use any of the Non-Taxpayer MLE, Taxpayer MLE, or even the Room MLE or Bi-Annual Exception to sign him. It's also likely that Kalaitzakis only gets minimum offers.

If Kalaitzakis becomes a free agent, other teams will have multiple ways to sign him as even teams without cap space could use any of the Non-Taxpayer MLE, Taxpayer MLE, Room MLE, or Bi-Annual Exception to sign him. If Kalaitzakis is waived and clears waivers, his value will likely have dropped low enough that he would only have offers for the minimum.