Well first thing happens is a industrial revolution kicks off, it too much of a power up that anyone who refuses is going to kicked around by those who does.
Germ Theory would change so much and prehaps stop the European plague, through Nigeria going to kick one off, COVID going to be fun, not crushing for a medieval place used to death but it going to suck.
I now picture Europeans running into World War 1 era tanks shouting, go back where you came from.