I added a new comment type, called Question. Unfortunately, it's hardcoded with "Add new comment" and looks exactly the same as any other comment type.
Let's change that to say "Add new COMMENT_TYPE".
I just copied /core/modules/comment/templates/field--comment.html.twig into my theme and replaced the hardcoded text with the field label:
{% if comment_form %} <h2{{ content_attributes }}>{{ 'Add new comment'|t }}</h2> {{ comment_form }}
Becomes:
{% if comment_form %} <h2{{ content_attributes }}>{{ 'Add new ' ~ comment_type|t }}</h2> {{ comment_form }}
comment_type is a variable available in the template - check the comment block at the top of the file for other variables you can use.
~ is how you concatenate strings in Twig.