Right because that's the only part that disappointed me or other people in TLJ
It's not about head canon, it's about the internal logic of the pre-established universe. A 29 year old emo boy who turned to the dark side a few years prior isn't going to surpass his master just like that. And again, it was shown in the movie anyway, he was inferior to Snoke. When Snoke attacked him with Force lightning, Kylo was about to protest. Why do you think he didn't try arguing after that? Because he couldn't do anything, he was powerless against him and he knew it. It's just logic, it's shown on screen.
Not to mention he almost died against the guards and was only fighting half of them. You think Snoke would have guards around him that he wouldn't be able to defeat all by himself in case of treason?
From the canon part of the wiki, after Sidious found Maul (could be any time after that, immediately or years later):
"As the Rule of Two mandated that only two Sith—a master and an apprentice—could exist at any given time, one of them had to die. Now that he had no further use for a teacher, Sidious disposed of Plagueis, killing him in his sleep."
At that point, due to his age, even if we assume he killed Plagueis when Maul was still a child, Palpatine already had decades of learning under Plagueis.
Not only that but he started as a Sith. Unlike Kylo, Palpatine never spent years learning as a Jedi. He started his training being introduced to the dark side, that's a massive jump start.
In TFA Snoke literally says he needs to complete Kylo's training. He sees he isn't ready, and reminds him in the throne room scene leading to the destruction of the helmet. Kylo got zero training in TLJ, he found a clever way to kill Snoke, that's it. So he is exactly where he was at in TFA. He is the same dark side user. He couldn't even best Rey when they Force pulled on the lightsaber, AGAIN. And meanwhile Rey is getting more powerful by the minute. If you can't see the issue, I don't know what to say. Good for you if you think Kylo is awesome, I guess.