mpv didn't ask to be on this list, was never consulted about being on this list and to the best of my knowledge has no problem with adaptive sync. If there is an issue exposed by mpv having adaptive sync enabled, then it should be reported to mpv, so that it can be fixed in mpv.
The only problem I could remotely imagine with mpv and VRR is that its display-resample mode tries to do something similar, and the two mechanisms will likely race each other to the bottom, but the display-resample mode is not the default and this is already a known issue on Windows so users wouldn't expect this to behave any differently on Linux.
In short, please don't try to make a list of all applications that are not video games, it is not conducive to having a good time on the computer.