The issue for me with VAR is not how it's operated, but that it creates two different codes of the game that requires two different set of refereeing processes.
The beauty of the game before VAR is that the 17 laws of the game are the same 17 laws for Liverpool vs City as they are for Ragball Rovers U12 vs Second-Hand Jerseys Athletic U12. If you dropped a PL ref into a youth 11v11 game, they wouldn't have to make any real adjustments to the actual refereeing of the game (i.e. the 17 laws), and vice versa. But with VAR, the new referee is now written into the rules. But clearly other levels don't have access to VAR. So that means that there will need to be a second set of game laws that refer to the VAR process, and whatever evolutions might happen because of it (sub rules for a start - does the ref allow subs on a VAR stoppage? If they bow to inevitable manager pressure and allow manager challenges, then that changes the set of rules for managers who don't have games under VAR). Essentially, this will be creating a "professional" and an "amateur" code, with different rules. Once that happens, we're open to a "closed shop" system, where non-league/semi-pro/amateur clubs are then shut out from the "Professional" system. But that's a broad-scope vision of what might happen
Right now, my only reservation with it is that it changes the game from a "game-for-all" to "two slightly different games, with slightly different rules, based on non-football resources available"
VAR only exists because there are TV cameras. It doesn't exist to "better the overall game". It only exists to better the televised game. For me, that's very much against the spirit of what the game has always been about - a game for players to play, relatively unencumbered, and relatively free-flowing with minimal time-stoppages.
VAR makes football into NFL, where TV becomes the evolution-leader, and not the needs of the players.