In Jira version 8.15, a new feature is implemented where the rich text editor is now available in the customer portal based on JSDSERVER-1506. However, it is really vague in the Jira 8.15 release notes on which field can have this feature and for now, this would only be applicable to the description/comment field.

Due to that, we would like for the feature for other text/multi-text custom fields to have the rich text editor in the customer portal in the future.