Assuming this is real and not an AI-generated shitpost, I think I might have an idea of what that is

It's a planet, specifically a gas giant, that has somehow been captured by the sun (or perhaps ejected by it)? without anyone noticing, or maybe they did notice and just never told the public

Look at >>40849359 and >>40849390: it looks like it's absorbing matter from the sun, but look more closely: in that case, the "tail" would be bright like the sun, and it would be thicker near the sun and narrower near the object, but it's the other way around, the tail is black, like the object, and it's getting narrower as it nears the sun

The sun is actually absorbing the object itself, not the other way around

Look at this thing: do you really think something so puny could ever be a serious threat to its existence?

tl;dr this isn't a sign of the end of the world