HTML Fields display with tags when you export in Excel format from List view.
1) Navigate to any list view which has an HTML Field.
2) Right Click on the headers
3) Export > Excel (.xlsx)
4) This will download the Excel file.
Expected behavior: HTML Tags should not render in the downloaded excel file.
Actual behavior: HTML Tags are rendering in the downloaded excel file.
This functionality is currently not a part of the product.
To remove unwanted HTML tags from list data, see the blog Rendering HTML in Exported Lists by a ServiceNow employee in the ServiceNow Community.
This information is also included in our docs site: List export.