They understand what they’re saying completely.

Do you realize how much of a batshit insane lunatic you sound to anyone outside of your echo chamber?

No, no they fucking don't. Toddlers don't "understand completely" just because you desperately want them to. Assuming for a moment this actually happened, pretending a five year old child is expressing their "genderfluidity" instead of mindlessly repeating what they hear around them proves nothing other than your confirmation bias.

This viewpoint is common among the single digit age

No, it's not, and it shows how detached from reality you are that you think this is anywhere close to even happening at all let alone a common occurrence. But who am I to doubt the unquestionable scientific reasoning of "All the Gen A's I know"?

It's not about the children though, amirite?