There is a thread on the Avid Audio Forum that with the release of Pro Tools 2020.9 the voice count has been halved, so now you can only play 64 stereo tracks instead of 128 in Pro Tools 2020.5.
UPDATE: We now know that this was NOT an intentional change. We have an honest explanation from Avid’s Francois Quereuil, Director of Product Management – Pro Tools & Control Surfaces.