The .navbar-nav class is missing from the menu--footer.html.twig file.

Yes, this causes problems for css that previously used .navbar-nav.

The new template also forces 'flex-row' class on the menu (with !important). I have multiple footer menus that display as flex column and this breaks it. I was forced to rollback and put the old menu--footer.html.twig into my theme's template file.

I am having this same issue. I can't seem to find a good template to change the classes. I also have menus that should not have the flex-row class and the update broke my menus.

I'm taking the drastic approach of altering the menu-columns.twig file. I changed the class manually on line 13 and it resolves my issue temporarily until there's another update. It would be nice for the maintainers to take this into consideration.