So there was a comment that claimed it was related to bad neck posture. Being a keyboard warrior in my late 30s at that time I suffered the same issue: Tinnitus and generally bad posture. I figured that even if that wasn't true, working on my posture might be a good invest either way. So a couple of YouTube videos later I started working on it. Turns out the process to straighten your neck - even after like three decades - with just some casual invest everyday only takes about a month or two. To my surprise the tinnitus was actually also gone.
As I haven't build a real habit around the exercises eventually a bad posture came back, and so did the tinnitus. Both are generally not as bad as they were before, though.
10/10, would do again.