Fancythat The 1700's were 500 years ago. Infamous didn't mean famous right up to yesterday, and its dictionary meaning is still the same. Unfit still doesn't mean fit - though it has only two little letters of difference, and if you see someone described as unfit for public office, you don't raise a cheer to find an honest man at last.
Young people have an excuse for not knowing the meaning of a new word, at first. They may not have met it before and it may be similar to another word. However, by the time they are "grown up" and constructing a website that displays "many infamous photographs" it is reasonable to assume that they had enough "education" to have met and understood common words in their native languuage, and to be able to use them without irony.
I would expect an infamous photograph to be of something like, for instance, Boris Johnson arriving at a party at no 10 during lockdown with a Fortnum and Mason carrier full of bottles of booze, or Jimmy Savile leering at a child in a wheelchair, not the well-known ones of past events and influential personalities that appeared in the website I linked to above.
Do English teachers no longer point out common prefixes like in- and un- added to words, which add "not!" to the words they are stuck to?
edible inedible
active inactive
digestion indigestion
fertile infertile
famous infamous
done undone
able unable
fit unfit
and many more.