Less a fluke, more of a pattern lately. Dems have been overperforming in most special elections since Trump took office again. Sometimes by a couple percent, and frequently by 10-20%. Only a handful of underperformances
For instance, they also flipped a Trump+21 distict in Iowa. They won by 5 points too
Will it hold up in the longer term? That's much harder to say, but it's not just one special election that's been a large upset
Even if there's no criminal charges, at least there are some groups that just filed civil lawsuits about the record keeping laws they broke
And note that Pardon powers do not apply to civil cases - only criminal ones