Overtraining is related to TSB if you want to talk about it in a cycling sense and use words and acronyms from that word-bank.
I think to an extent TSB and CTL are over-rated because the optimal adaptations can occur at different levels in different people. It might also depend on the training phase. If you're working on your threshold and/or some VO2 work, you simply can't do workouts like that every day and/or also have huge base rides in between. You need more form to hit those workouts.
You don't need a lot of form to do steady state, tempo, or z1/z2 training. That's where I'd pay more attention to overall CTL and TSB. Folks tend to ramp their CTL too quickly and for too long without any plateaus (breaks).
That's overtraining. You literally make yourself physically ill sometimes. Adaptation stops (or you regress).
So, I'd look at these things separately. You can have a fun hobby in bike training and looking at the numbers. You can also have a problem a health professional needs to help with.
I wouldn't really use the word overtraining together with addiction. Athletes who don't need mental health care can over-train. Athletes who have an addiction or mental health need might very well have never actually over-trained in their entire lives.
I'd nail the mental health aspect first. Then worry about the actual meaning and recognizing "overtraining".