Service Portal Service Catalog Instruction field with h1 tags does not override the "More Information" header
Upgrade to Madrid changed how to override the "More Information"
If you want to overwrite the "More Information" for the Service Portal you will need to
create a new widget
add the tags to the "Body HTML template"
Add a new macro with label variable
point the variable in the "Type Specifications" tab widget field to the new widget.
You would have to de-activate the old label
I will add some screen shots from our OOB to show how we got this to work in service portal.
If you need this for the Normal UI not service portal you would have to create ui macro with jelly to accomplish this.