Ted Lasso will definitely have the most fics. Other than TL and The Locked Tomb, I think this might be The Good Place's last year of eligibility. It's got well over a thousand fics without filters and it's rounding on 800 with them. It's a slow grower and a closed canon, but it gets a new fic every few days, so if it's still in next year, that will definitely be it for it. Maybe Disco Elysium? It's been around for a while and is still way under the limit, but it had a lot of its growth this year.