I also don't know how to beat writer's block, mainly because I don't struggle with it. Not a lot, at least.
But what I do when I AM stuck:
First, I look in my notes app. I have a folder for every single fanfic and note the most random things down in the middle of the night, in case I'll forget.
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lol here's an example of Nepenthe's folder.
I also have private collections on TikTok for my fanfics. I put sounds to edit the fanfic with in there, but also prompts, etc.
Sometimes, it's better to just focus on other things, like going on a walk with your favorite playlist on. Your mind will come to new ideas and motivation to write.
If you're stuck, you can also have a look at comments. What do readers get excited about? If they made up theories, just get inspiration from that.
Or ask someone for ideas. Look some things up online. There's many things to do.
