This became a global privilege so you can find it on that page. Seems like the language key wasn't removed from the settings page so it is still showing up in ACP search.
BUG: Do not download files
File = 1,69 MB
Have you tried changing the client_max_body_size in nginx?
Even though the default is 2MB, the actual data being transferred may be over that for the file you are uploading. Try 4MB.
@yariplus ha-ha, yes. It was in this. Now everything works fine, thank you!