That Hunter Biden had problems with the IRS, including some violations that were being looked at by prosecutors, is old news. This is from July, of last year, but since it was printed on a news source forbidden to conservatives they might not a heard of it before.
My guess is that the powers that be at the IRS decided that so long as Hunter paid off what he owed they wouldn’t bother with a prosecution. This irked a MAGA employee and so he decided to blow the whistle.