I have run into a rather widespread "dead links" issue, entirely of my own making though I didn't realize it was going to turn out this way.
When the COVID lockdowns went into effect, I decided that rather than twiddling my thumbs I would get serious about exploring the family genealogical woodpile.
Being new to the "game" it never occurred to me that when I cited a source found in the Ancestry public library version that was made available to home users for the duration (since the libraries were closed), eventually those links would go bad, and I should try harder at the outset to find an alternate source (Familysearch, perhaps). Or to just download the document to begin with, by screencap if nothing else.
So I now have a huge number of sources on countless profiles linked to "ancestrylibrary.com" for which outside (of the library) access no longer exists. As I run across them, I'll look for the same source document on Familysearch, and if it can't be found there, it goes on a list I'm creating for a time when I will physically go into the library and start downloading the broken-linked source documents.
So the overall lesson going forward is, when you (or I) find an actual birth or marriage or death (or some other) record staring at us from the screen, SCREENCAP the bloody thing and save it! So at least we'll have a copy of it if its online source vanishes at some future point.