I have the same problem on my wife's iPhone 8. We updated to iOS 14 and Evernote 10.0. The app always crashed immediately after trying to open it.
The iPhone language setting was set to German (Switzerland) and the preferred order of languages was set to 1. Swiss German and 2. German.
After putting German first, Evernote opened without any problems.
Weird behaviour! At least she can use Evernote again on her iPhone.
Thanks for your help, @Marc-ch