Replacing a letter with a little x is 100% a queer theory/TRA thing and I don't know why they're suddenly rejecting it, or why rejecting it necessitates pretending their own PC term that they invented was being imposed onto them externally.

"Womyn" already existed and was used by radfems, as well as a few variants like womon, wimmin. The idea was to reject how the words "woman" and "women" sound like women are defined in relation to men (the etymology is more complicated than this, but that is nevertheless what the words "man and woman" and "men and women" look like and how most people read them).

"Womxn" was not one of those variants; it was invented by TRAs and that crowd to create an alternate spelling of "woman" that wasn't tainted with the terfy connotations of "womyn". Their reasons for an alternate spelling of "woman" was to render the term "gender neutral", according to their definition of gender neutrality which involves erasing recognition of sex rather than rejecting gender roles. They rejected the already-existing "womyn" to distance themselves from radical feminists ("TERFs") and emphasise their differing motivations for coming up with it. Look at "Latinx"; I don't know which came first (though I suspect it's "Latinx"), but the repeat of replacing a letter with an x is meant to signify that the same people—the correct people—came up with it and their motivations are the correct kweer theory motivations. It's intended to reinforce TRA/queer theory group identity. I don't know why these TRAs are pretending this example of queer theory shit was invented by anyone other than their own community.