Kenobi and Maul canonically have improved as duelists from when they've last fought:
"The actual duel is very short, how did you come to the conclusion it had to come this way?...(feloni) If you talk to a lot of people who sword fight, they'll tell you people who are very good don't have long fights. So that scene, its a homage to the 7th samurai. I think on one level people would be excited to see a prolonged lightsaber fight. But I just never really saw the confrontation that way because to do that is to say the characters don't have growth "
Now lets note that due to kenobi's emotional growth as a character(not circumstantial), maul could not defeat kenobi suggesting kenobi is a clear superior to maul:
''When pressed, because Obi-Wan is protecting someone else in the end, he does fight. But because he is so true and knows who he is in that moment, you can’t defeat that''
So Ben Kneobi is>>Rebels Maul who is at a minimum >TCW Maul
Sod Maul is not only more powerful as a force user than tpm, but is more powerful "in all aspects" including "skill, speed, and strength" making it clear that SOD maul is also superior as a duelist:
Upon his return in the Clone Wars, Darth Maul's becomes more powerful.
''Maul had grown more powerful since the last time he’d been in Sidious’s presence, before the Neimoidian invasion of Naboo.''
So
Ben Kenobi>>Rebels Maul>TCW Maul>TPM Maul who is one of the most skilled siht in history and was superior to one of the most skilled swordsman in the history of the order(qui gon)
It could mean many things when he says "the characters don't have growth". I think by "growth" he's not referring to their growth in power, but instead he's referring to their growth in that they've grown accustomed to each other after so many duels and know how the other fights. At least that's my interpretation.
The "growth" isn't even needed here. Whats important here is the "people who are every good don't have long fights" which implies that rebels Maul and kenobi are "very good" in comparison to their tcw counterparts had "prolonged lightsaber fights". And given the context of the quote, I'd say growth here is pretty clearly in reference to skill level(being "very good").
One of the reasons for the shortness of the duel(in addition to them having fought each other multiple times) is that they've progressed as duelists
I could be wrong, but I don't see how a really short lightsaber duel like that would show how the characters had growth as duelists. It definitely shows how Kenobi had growth, but not Maul lol
Its probalably feloni bsing. But thas still canonical bs that puts rebels maul over tcw maul and logically over sod maul as well(though technically speaking, if you stretch crap enough you could argue that rots and sod versions of maul and kenobi are exempted from this)