As of 15 minutes ago the article is no longer stating he pled out on the gun charge.

Currently it states

Hunter Biden, the son of President Joe Biden, will plead guilty to two tax misdemeanors and struck a deal with federal prosecutors to resolve a felony gun charge, the Justice Department said Tuesday in court filings.

And then goes on to say

“A firearm charge, which will be subject to a pretrial diversion agreement and will not be the subject of the plea agreement, will also be filed by the Government."

My guess is they more-or-less dropped it as they didn't want him challenging the constitutionality of The Gun Control Act of 1968 like he said he would.