Even when the user-tier is the same, JIRA reports that legacy licenses are not compatible with the newer licenses. This leads to plugins not working and customer advocates needing to re-issue licenses.

Resolution
Fixed with UPM 2.18.2 release. Please upgrade using Add-on Manager or from Atlassian Marketplace.

Reopening the bug:
This issue has resurfaced starting with Jira 8.20.8 and being observed in Jira 8.22 release as well with the same error: "Legacy enterprise validation checking".

Update September 15, 2022

We made an investigation and confirmed it’s a false positive caused by a wrong regular expression used by the log analyzer tool which is bundled with the "Atlassian Troubleshooting and Support Tools" plugin.

Every day, the log scanner retrieves a product-specific XML file that contains the RegExps from confluence.atlassian.com.
If your Jira instance is connected to the Internet, you should have the latest XML file, and the message "Legacy enterprise validation checking can cause erroneous type mismatch" should no longer appear in the log analyzer.

If your instance does not have access to the Internet, you can manually download the last version of the "Atlassian Troubleshooting and Support Tools" plugin here following the instructions.
Updating apps