Currently we get that data from TMDB.
The way they add anime seasons don’t make it possible to link with aniDB or MAL, since the seasons from the same franchises are added in the same page(and sometimes, different seasons are added in the same season), OVAs are added as specials and movies are added as movies.
For example: Demon Slayer: Kimetsu no Yaiba
Each season on MAL is a different page, the specials are grouped on other pages there aswell. Some, don’t even exist on MAL.
As for the movies, we also have the special movies that aired on theaters in the beginning of each season, the anime databases don’t have those since they have the same content as the episodes:
The browser extension is currently broken, sorry. Google made me fill out additional forms due to new rules/manifest 3.0 migration and from what I gathered they don’t like the way I handled the “indexing” and never followed up (the store listing was taken offline ). Attempts to port it to Firefox-based browsers (which I swapped to due to Google’s moves regarding the whole thing) have been stalled due to compability issues with indexedDB . Should probably look into this again some day or at least publish the userscript again. Maybe AI can help a lazy dummy coder like me .