This meme is the classic them vs us, which by itself is how facism starts.
The world is not so black and white. If I was American and could vote, then I would vote some third party that actually represents my views, since that is the only choice that would make sense. Also tankies criticised both trump and biden as we'll, it's not bad to be against the mainstream, if both options are shit.
If everyone would think more critical this situation would not exist.
Nobody wants it to be us vs. them but as you say fascist movements are us vs. them. When there are fascist movements in existence it is us vs. them whether you want it to be or not because they make it them vs. us. It doesn't matter how hard you hold your eyes shut and cover your ears, the fascists are there and if you're not in their movement they are against you.
It's not all doom and gloom yet. Most fascist movements fade away and die out. But it behooves the non-fascists to help that outcome occur. Pretending fascists don't exist doesn't help achieve that outcome and risks there being a very doom and gloom outcome.