Perhaps this forum post might help?
Your SharePoint list fields type should be the same type as used in PowerApps fields type. i.e. if using the dropdown in PowerApps, you need to make sure you are using Choice in SharePoint list for the same field.
I doubt this is the problem, @Muzammil .
I've encountered this error numerous times and the only solution so far is throw away the fields and re-create them. It's a back end problem that should be fixed.