That and Mallow's goal has nothing to do with battling.
But Mallow doesn't really get a lot of goal development, and when she does it's ironically cut off most of the time for her to, guess what, BATTLE. A very lame one sided battle against a jobber villain, but still a battle. She's had all of two focus episodes right now that have really tried to put in some full attention to her character and her bond and use of her Pokemon (and even those pull short cuts here and there), otherwise she's kinda doing the same generic things other third wheel companions get.
While Kiawe, Lillie and Sophocles haven't had terrific amounts of limelight, I still think they have had something that equates to a small character arc, especially due to them playing off the series' recurring 'big fish in small pond' motif like Ash does (ie. they're gifted in their element, but out of it they're hopeless buffoons) giving them some agency and some agenda to expand upon, along with some fallibility and good old humour value. All four of them have also had at least one episode that plays off as a near full and impressive character study. They feel reasonably complex as characters. Hell I could argue even Rotomdex has some recurring characteristics and goals to keep playing on in his limelight in a palpable way.
Mallow and Lana don't really have this, they lack specific flaws or weakspots most of the time, even the stuff irrelevant to their goals they're usually allowed to win easily, while their goals themselves are ironically limited in any form of expansion (then again how can you add some daunting new personal challenge to 'making bigger bubbles'?). Their episodes are mostly the ones reliant on external dilemmas like their family or antagonists or COTDs being the problem rather than any need for improvement in their own characters. It also means they can't develop on their agency, even ensemble episodes like the Ultra Guardian ones, which are largely the group fumbling around trying to figure out how stop a UB according to their niches, they're usually in the background doing nothing.
To make things clear, this isn't me complaining about the episode itself, it was pretty impressive, but I'm not on the whole "this episode completely fixed Mallow's character' bandwagon.