ACE throwing unable to decode Symmetric JWT token for multiple instances

Hi all, a number of our app customers suddenly started seeing JWT errors accessing authenticated pages today in a Jira Connect App.

Our app is using standard Node atlassian-connect-express and it is now throwing: Unauthorized: Unable to decodeSymmetric JWT token: Error: Signature verification failed for input: eyJ0eXAiO…. with method sha256 for some (but not all) customer instances.

The only way we’ve been able to fix this is to manually uninstall and reinstall the app in the environment.

Q1. Anyone else seeing this start today/recently?
Q2. What is the right Atlassian customer/partner support portal to raise this in to get Atlassian involved. Local support for our instance, marketplace support, partner service desk, ecohot, other?

Thank you
Chris