Leetx won’t give you an account just to post one thing, those are for people who promise to provide regular content and pass a questionnaire. You can go into their IRC channel and see if you can find someone with posting privileges who’ll post it for you though. You can also just start seeding it on your own and add a few basic trackers to it without uploading anywhere, DHT scrapers will find it and it’ll start to appear on certain trackers for those and spread out into the wider ecosystem as people use search tools like jackett or the arrs and find it, with luck one of them might even re-up to a private tracker for longevity. Archive dot org is also not a bad suggestion but things can pretty easily get taken down from there as well, it’s kind of luck of the draw how long it stays up, could stay up years, could be taken down in weeks.

The pirate bay might still allow new accounts to upload, my only guess at the moment.

If it is particularly rare and you can add big public announcers to it and seed with a DHT client someone here might be able to upload it to a private tracker for you (if they know the name). Otherwise at least with DHT on and some open trackers added people will find it eventually though it may take a few days or even weeks to start propagating and if interest is low it could take months before anyone tries to download it but such is the way of things. Make sure to name the torrent and files accurately with the movie name, year, source (like bluray), etc.