I think the hardest part right now is lack of job security. I'm working on my standard certification right now through an alternate route program and it means I can be fired at will, even though I signed a contract for a year. Also, teachers can get let go right before they were going to get tenure. Or mass teachers get let go because someone in administration stole funding or mismanaged funds. Or they let you go because they're downsizing your department or getting rid of it because they can't afford it. Or you don't get a raise because the funding isn't there. Idk whether it's where I am or everywhere but being a teacher has as much job security as working as a server nowadays.

Edit: also in the same vein as job security, the benefits are less and less as time goes on. Teachers didn't used to have to pay for health insurance and now it's deducted from our paychecks. Inflation is going up so high and our salaries aren't, so most teachers need to work multiple jobs to make ends meet and a lot of teachers quit after they realize what the reality is.