In all seriousness, Ellen's thrilled to have this option and would only pretend to be disappointed in jest, but this is a comic strip, darn it. I can't show the part where Nanase calls her out on her joke by glomping and tickling her. That would ruin everything.
Sidenote: I swear I don't have a thing for Ellen getting tickled. At least, I think I don't? I do keep suggesting it for some reason.
There are established lore reasons why Ellen's TF beams don't generally affect clothing. These reasons were established before I took a moment to think "gee, that might make it awkward and difficult to use these in stories given what I'm not willing to actually show".
With that in mind, it FINALLY occurred to me that, if Ellen can get different results by putting her hands together, she could also potentially get modified results in other ways. This way, she can make clothing fit just fine with FV5 without it being an absurd retcon.
I mean, it's absurd, certainly, but not specifically an absurd retcon.
Much like Greg when zapped full power with FV5, Nanase winds up with less muscle tone in FV5 form. That doesn't mean she's suddenly lost all her strength, however. She could still throw a couch in anger at you. It's just less obvious that she can throw couches at you.
Worth noting that Ellen's long list of "like FV5, BUT..." spells would include one or more spells that would keep Nanase's muscle tone. I just wanted to show that base FV5 can result in that sort of change when used on women, too.