Problem visualization of description of a custom field on issue create screen

Hi, I’m having trouble with HTML description with the custom field of the plugin that a manage.

Where can I find some documentation where is described how to handle it.
I have search " https://developer.atlassian.com/server/jira/platform/creating-a-custom-field-type/ " but I didn’t find anything helpful.

I have enable HTML in field descriptions and list item setting. But It seems that the description is not read well.

Regards,
Emanuele Picariello