Filler words carry meaning, even if they don’t have specific definitions in context. Like, “like” has a dictionary definition, but if you use it as, like, a filler word, you aren’t using that definition (necessarily), but it still conveys something about how the speaker is thinking. They don’t just pop up in speech at random. I like catching them and trying to interpret why speakers insert them where they do.

Like, “lowkey” is usually* sometimes used to soften harsh language e.g. “I’m lowkey gonna murder Sarah if she doesn’t stop chewing her gum with her mouth open”. Kinda how “kinda” works as a filler to tone down whatever is being said. I don’t actually want to murder Sarah, I just kinda want to murder her. I don’t even know if I would call them “proper filler words” in the same sense that “like” is, since they do have a particular function that “like” as a filler lacks. More research is needed it seems.

For me, I let 'em fly. If I had to deliver a speech I would probably include fewer than I usually use in casual conversation, but I don’t hold with the rule that they’re strictly to be avoided. I think they’re neat.

* edit: I just know how I’ve heard it used, I have no idea how it’s usually used. I’m lowkey not in the lowkey demographic.