> I could never enjoy tasks assigned to me when they're dull and basic things I've mastered.
If you do need more interesting work and can’t shift teams then find a new job. You will eventually find yourself needing to do the same again after you’ve mastered the new challenge. Keep it up and you will run out of leaps. However if you want to exist in a place for a while you need to accept that not every project, task, idea will be exciting work. Once you accept this, it also opens up doorways with what else you can do with your time. Since you have a mastered skill set, these menial tasks should not be weighing you down to free yourself from the drudgery of work.
> As for being proud of my work... well I'm always proud of my work. I still burned out. I don't want to even touch the things I'm proud of.
You should always be critical of past mistakes and look to correct but you should always put your best effort forward. That is what pride in work means. You shouldn’t have to admire every piece of work you deliver as a masterpiece, which is what I assume you mean by wanting to touch it. You should always carry a positive mindset about your work and not treat each success and failure in your life as some sort of definitive legacy. Invite in and operate under best intentions.
A lot of my advice is about how it works in harmony, not some quick instant burnout solution. Resting is important as well (breaks, vacations).
Anecdotally I was recently hired at a company that is in dire straights. This weighed on me heavily for the first six months, eventually they shrunk my team. However I cannot afford to get burned out. So the only options are to extract as much of the burden from me by being a cog in a bullshit factory or find a new job in a psychotic job market.