Is it possible to downgrade to iOS 14 from iOS 15

You cannot restore/install an earlier version of iOS/iPadOS than is currently installed on your iPad. 

All System Updates are digitally signed by Apple - and can only be installed whilst the digital signatures remain valid. After release of a new or updated iOS/iPadOS version, the immediately preceding version continues to be digitally signed by Apple for a short period - however, usually within a few days, Apple will revoke the digital certificate with which the earlier version is signed.

Hey there,

No , Is there any reason why you should like it, maybe we can help if there is any problem you face