This is a continuation of a baseless urban myth.
Wikipedia has a complete history of the Litter boxes in schools hoax, with multiple debunkings.
Starting in 2021, a false rumor alleged that certain North American schools were providing litter boxes in bathrooms for students who "identify as cats", or who participate in the furry or otherkin subcultures. Various American conservative and far-right politicians and media personalities promoted the hoax in response to several school districts enacting protections for transgender students. Many news outlets, fact-checking websites, and academic researchers have debunked such claims, and officials from every school named by those promoting the hoax have verified that the accusations are false. The claims have been described as internet trolling, fearmongering, and anti-transgender rhetoric.
The claimant, "MallyMouse", admits this litterbox rumour "might not have been true", but then goes on to insists that "this" definitely is - and goes on to claim that children may be rounded up by animal control... but the lawmaker himself admits his bill is based on the the litterbox issue and the language is sarcastic.
Rolling Stone explains:
Humphrey tells Rolling Stone he was inspired to write the bill after hearing several reports of students disrupting school while engaging in animal-like behavior. He cites two such alleged incidents in which a grandchild of a friend took to crawling down the hallway while wearing a leash, and another where a student distracted classmates by meowing like a cat. He seemed most concerned, however, with the idea of students requesting litter boxes in the classroom, a favored talking point among right-wing politicians that has been debunked.
As for the whole animal control thing? The representative admits that it’s a bit of a joke. “If a dog showed up at school, you call animal control. And if you want to treat these people as actual animals, you call animal control. I’ll be happy to rewrite the language [to replace ‘animal control’ with mental health professionals]. But right now, I put that in there to make the point. A sarcastic point.”
So, we have a joke bill, to solve a mythical litterbox problem (that MallyMouse knows is false) and one or two unofficial anecdotes.
She has used hyberbole to exaggerate the (non-existent or almost non-existent) issue. If the schoolchildren were really commonly dressing as animals, schools would not be denying the existence of furries and it would be an obvious phenomenon to anyone who walked past a schoolyard at recess.