I thought eggs are not meant to be turned after day 18
Unfortunately broody hens aren't active on this forum so we can't tell them what they can or cannot do. So they do what comes natural to them.
We do not turn the eggs after 18 days because we don't need to. Actually you don't have to turn chicken eggs after 14 days, the benefits of turning have occurred by then. It's just convenient to stop turning them when we raise the humidity and go into lockdown. But because they don't need to be turned doesn't mean it hurts to turn them. I imagine you read that about not turning them on this forum. That doesn't necessarily make it correct.
Trust your broody hen. She knows more about what she is doing than any of us on here.