OMG you've nailed exactly what I've been feeling for the past six months or so. :/
I've never personally experienced true burnout, but I also have a policy of taking it seriously and making sure that I do something about it long before it becomes a permanent trauma, and I have had to call a couple of multi-week vacations with relatively short notice, or perhaps announce a vacation a month before the end of some important project. Sometimes it's even as simple as waking up on Friday and just realizing that today is a "Nope!" and taking it off. I think if you nip it in the bud you often may not even need to do it that often. But take it seriously.
And if your job won't let you do that, take seriously the possibility of finding a new one. Yeah, finding a new job sucks, but permanently burning out sucks way more.
Sometimes I'm just really not feeling like work and take a day off. Unless something important is happening that day, management could care less. Sometime I stay up late the night before because something caught my attention outside work and I couldn't put it down. I'll take the next day off.
Helps that my company have a seemingly generous PTO policy (at 5 years it a bit more than a day per paycheck (every other Friday)). If you're not a problem employee everyone just wishes you a good day.
But, I don't think I really felt burnout before the pandemic. Working alone has pushed me to the point where focusing feels like a strenuous task. My most productive stints (in my subjective self-opinion) are when I'm working with other people on a call (my role is basically half research / half implementing it).
Part of me hopes going back into the office will help calm my mind but I'm just not sure.
I'm on medication now, going through therapy, and still at my current gig doing better than ever.
So, what I want to say is that if you are concerned you are burnt out - it's very possible work is burning you out, but it's also possible to seek treatment before making a big decision like leaving a workplace with tons of great benefits and healthcare to support you.
I also suffered burnout at a job, but I didn't realize it until I was receiving therapy related to my anxiety. I don't know anything about meds or ADHD since that isn't anything I have experience with, but I think it's worth doing some introspection on one's self to see if there are thoughts or tendencies that are also there underneath the burnout.
To be clear again, I am not advocating for everyone to assume their burnout is due to some sort of mental health issue - but to also not discredit exploring this prior to making a big emotional decision like leaving a job, and possibly making symptoms even worse if not addressed.