I am not a teacher but work in a profession that goes into schools, what I have learned about the job that I would find stressful is :
living by very tight timings - everything is timetabled and staff are expected to manage the unexpected within that - a child who shares a safeguarding concern, a conflict between pupils; unexpected environment issues like a classroom becoming unavailable
What do I notice - people dont eat or drink or go to the toilet without always noticing - that takes terrible toll on the body.
Emails - teachers often read emails day and night and over the weekends routinely - this is a central way of communication in schools because of the structure of working in classrooms - this leads to limited time away from the job - this is bad for well-being. Emails can lead to miscommunication between staff and managers - increasing stress levels if there are tensions.
Now parents use email it changes communication where talking would have taken place face to face there is more time needed for responding - its good for real time information sharing, not so good for a system set up to deal with meeting in person.
Very little thinking space is available in teaching - teachers are always dealing with groups or individuals - there is little time to process without being responsible for monitoring what is going on in the environment and being ready to intervene.
Some of the leadership positions offer different opportunities and I have met amazing people who have stayed in teaching and gone into leadership. Its not a role I would choose or recommend to someone I cared about.
Good teachers make a huge difference to children and young people - literally life changing.