Upgrading Confluence to 7.12.2 and later versions from 7.4 will result in custom fields being shown in lowercase

Issue Summary

Upgrading Confluence to 7.12.2 results in Custom Fields from Jira getting displayed in lower case and disappearing from field selection section

Steps to Reproduce

1. Jira v8.17.0 installed
2. Jira and Confluence are linked by an application link
3. Jira Issues Macro is added to Confluence page with custom fields shown and populated
4. Upgrade Confluence to 7.12.2

Expected Results

Jira Macro on Confluence is displaying all fields as they were before upgrade

Actual Results

Jira Macro on Confluence is showing all custom fields lower case
Some of the fields are not available for selection in field list
Some custom field data might not get populated

Workaround

Re-adding macro to the page will fix the custom fields
Upgrading pre 7.12.2 Confluence to 7.13.1 will not result in custom fields being displayed as lower case, but if custom fields got broken by upgrade to 7.12.2, then upgrading to 7.13.1 will not fix them.