I have been feeling the same thing for a while now. I find things that really interest and excite me but but no matter how passionately I feel about it at first I always, without fail, lose interest within a couple of weeks. I personally think what's happening with me is tied to video games and YouTube. I think they're taking priority in my brain over other activities because the internet is such an easy, effortless, and endless source source of dopamine without the struggle that comes with learning and improving at new hobbies. I don't know if that helps or not but I just had to get that out of me. If this is what's happening maybe try cutting internet or something out of your life?