They have to. I mean legally they cannot consider that evidence. If they keep bringing it up in jury deliberations, and that gets reported, it would be a mistrial.
However, you’re right in that it cannot be erased from a person’s mind… the phrase I’ve heard used is “ringing the bell” which is when a lawyer might mention a persons prior convictions, but that gets objected to and stricken. But the bell rung and the jury knows.
If they don’t, and they say they aren’t, it is a mistrial.
If they don’t, and they keep their mouth shut, then no one knows.
Connected.