Maybe they have a non-standard interpretation of thumbs-down – as "thumbs-down to this fact" not "thumbs-down to you for pointing it out"

When you only have eight emoji reactions to choose from, people are bound to get creative in how they use them.

I have noticed this behaviour happening more often too, it's very confusing. Usually when texting with younger Gen Z people.

This has always been happening

We lived through a generation of agism at millennials and now we're turning around and doing it at Gen Z. It's unbelievable.

Or they're from Eridian.