Apple notes claosing again and again ipados 18

İ am a student and in class iam using ipad for lesson book for example general chemistry and after ipados 18 update , while using pdf on apple notes the app closing it self like every 5 or 10 minutes to day 9 or 10 times i experience it , how can i solve this problem , already restart device also i deleted the apple notes and download again but after that 2 times it close itself while in class it too annoying because i am writing some notes on pdf book, pls help me (ipad air 11 inç m2) i just bought my ipad 1 week ago and after update this problem too bad for apple for me normally i am a samsung user there is no problems like this