Burnout is absolutely real and I have been there. The reality in terms of working hours and lunchbreaks and reasonable deadlines for stuff and out of hours and weekend working etc is that you need to set those boundaries for yourself, no one is going to do it for you. Your colleagues won't, your boss won't. You have to set them or you just get walked all over. This is still a learning process for me but I'm working about 20 hours per week less than I was and also commuting less, and I'm feeling the benefits.
(1) Take your work emails/MS Teams etc off your personal phone, or at least log out of them at the end of your working day.
(2) Literally put your lunchbreak in your calendar as a re-occuring commitment daily.
(3) Schedule focus time in your work calendar to work on each project uninterrupted. If nothing else, it allows people to see how busy you are when they are trying to allocate you more stuff.
(4) I have my work monitor (note - not the laptop, I don't risk losing any work) on a smart plug. It literally switches the screen off at 8pm. I can manually switch it back on, but it's a good reminder to me to ask myself "do I really still need to be here, everyone else logged off 2-3 hours ago".
(5) If I have after work commitments, I put them in my calendar as private, with a 45 minute before alert. This again prompts me to think - is what I'm working on really urgent, or shall I finish up here, get changed and go to the thing.
(6) I have an absolutely no work on Saturdays rule. If I have to log on on Sunday afternoon, so be it, but I absolutely refuse to work Saturdays now under any circumstances.