WordPress is stripping the Alt tag’s quote marks from images where Alt is not set, but leaving the word ‘alt’ creating problems for ADA compliance

How do I get around this? For ADA compliance I specifically need alt="" on some of my images in a wordpress site, however wordpress is stripping the Alt tag’s quote marks from images where Alt is not set, and just leaving the word ‘alt’ without the quotation marks. How do I make sure the Alt tags are left intact with their quote marks? I just need it to say alt="" instead of alt. ! 😀

Do I need to re-register all my images in the media library after a migration?

I’m moving a 6+ years running WordPress site to a new (Azure VM / LEMP) server, taking the time to upgrade Ubuntu, Nginx, etc, and trying to clean up years worth of grunge. ~20 authors, 40k posts, 6+GB of images, etc.
I’m moving things over manually, copying the uploads folder over, so the images aren’t registered in the Media Library. I’m looking at some plugins to help, but am wondering if it’s necessary to re-register all the old images into the Media Library? They’re all properly linked in the posts, etc.
So, wondering what kind of performance gains, if any, I would get from just not bringing (most of) the images back into the Media Library? Most of these will never be used again (the ones that will I will def get into the ML). Is it worth the bother?