Hello.
In the next file Mega Menu use h2 header.
md_megamenu/templates/frontend/md-megamenu.html.twig
This provides some ADA errors, if we doesn't set h1 before mega menu that can not be done sometimes for different reasons.
Please, advice.
Tue, 01/15/2019 - 09:45
Hello
Almost Drupal blocks use h2 tag for block header
If you have problem with h2 tag, you can use other tag by creating a file named md-megamenu.html.twig (in frontend theme), copy content of template module megamenu and modify to your needs.