That looks like a very effective defense mechanism for recovering from burnout. Maybe the reason you didn't noticed it as burnout is that you recovered while it was still mild.
Maybe but I don't think so. In my mind, burnout requires some point of burn. In my experience, these jobs are just cush and have a nice paycheck but lack any type of burn. I usually get paid well to do something I feel is trivial but they see value in it. The job doesn't actually challenge me intellectually and maybe it was fine when I liked the people or was building out the process but then over time it's not enough to keep my mind from wondering (and sometimes the people change, so my engagement tanks because of that).
I've had burnout too (I think). It's stressful as fuck. What I described above is not, because I don't care at all. My burnout situations have crashed hard and usually bleed into my personal life more so.