NBA 2K21 patch notes are here, and also the huge 26GB upgrade address several bugs and glitches.Which bugs and glitches aren't detailed currently. The patch notes only detail generic information like firmness and user experience improvement.
NBA 2K21 started with a high number of bugs, such as the return of the infamous aisle glitch. My athletes occasionally don't appear, and there are various animation glitches during matches. The most egregious bug was for pre requisite content and VC not looking in the match.