AI has been able to crush heads up (2 player) No Limit Hold Em for a while now and 6 player for a few years. In that time frame though, a lot of other games have gained popularity, and playing a mix of games in the same sessions. AI/solvers are also normally optimized at certain stack sizes (measured in poker as how many big blinds each player has) and do not do as well in very deep stacked games. The trend of playing more games, newer games, and playing deeper will probably continue to stay ahead of AI, and people that study it. I would not play low to mid stakes NLHE online at all on any side at this point personally, just too likely to run into someone using assistance that will crush you easily.