Teachers in private schools can choose to quit public schools when they are older if they don't consider "career establishment".

In my thirties, I still have some opportunities to change jobs from private schools to public schools. Some public schools will launch "temporary posts" from time to time.

Teachers in private schools are all over 30 years old. Some ethnic minority areas or minority public schools will relax the age to "35 years old" or even "40 years old" or "45 years old" when recruiting teachers. However, the requirements for applicants in other aspects have increased, so some older private teachers can try to apply.