The exact numbers for when it messes something up, but keeps running, are unknown and highly ubpredictable.

According to above post, about 10% of firefox crashes (more numbers found in the post) are caused by this stuff. It’s not unreasonable to say those crashes could’ve had the bitflip happen on content instead, changing maybe a character on the page or something.

Note that it’s not 10% of users, as that’s reslly hard to figure out. Someone with bad RAM will likely crash more often.