Can we try removing this Xbox as your main account's home console to see if that helps? We've heard from a few people who have said they were no longer stuck as a Trial user after that.
Open up your Xbox Settings > Personalisation > My Home Xbox > Change from Home Xbox to Not Home Xbox. If you've ever game-shared with that account reach out to your friends and make sure their console isn't set as the Home Xbox for your account. After that try launching Battlefield V again and see if you have access to the full game.
If that works you should be able to set your console back to your Home Xbox on your main account.
/Kent