The trap is believing that passive watching is enough. It's like delivering packages for 17 years while listening to podcasts about technique - you're not gonna get faster just by hearing people talk about speed. Pronunciation is a muscle, you gotta activate it.
Where everyone messes up: they don't work on targeted phonetics. You probably have English sounds you never made in French (the 'th', the rolled vs non-rolled 'r', the diphthongs), and hearing them pass by in a TV series isn't enough to pick them up. You really gotta isolate them, listen to them slowed down, then reproduce them out loud. Look for specific resources like Forvo or YouTube videos on English phoneme pronunciation. Spend 15-20 minutes a day just on that, not binge-watching series.
Then force yourself to actually speak. Discord is cool but a lot of people don't listen carefully. Try conversation apps or conversation groups where people actually correct you. Grammar is the foundation, yeah, but if your accent makes words unrecognizable, there's no point having perfect sentences. In 17 years I know you gotta practice actively to really progress, not just kill time. Apply that to your accent and it should move.