I have question, if I want to restore from backup which was made on iPad on iOS 14.8.1, will i be able to restore to the new iPad on iOS 15 or do I have to update my older iPad to iOS 15?
Which is a huge PITA sometimes. You have, like 15.0.1 backups, and it won't restore to a 15.0.0 device. Which means you need to initially set it up, upgrade, then reset it fresh again, and then restore.