As I read it, it has three layers to it.
First, Trump is losing a lot of money, and he may lose more when some debt he’s guaranteed comes due. We’ve long known his “amazing businessman” façade was just that, but the report does add new details.
Second, he pays little or no taxes most years. This is supposed to shock us independently of the first layer, but it mostly just follows from it: People who don’t make money don’t pay taxes. Also, Trump has bragged about not paying taxes, so it’s not as if this is new information either.
Third, Trump sometimes tries to reduce his tax bills in borderline ways that may or may not be kosher. This isn’t really a surprise either, though of course if he’s actually flouting tax laws the IRS should call him on it. The biggest item here, a huge refund of past taxes he claimed when he later lost money, is the subject of an audit — though it’s an unremarkable feature of the tax code that businesspeople can “carry” losses from one year to reduce tax liability in another. (This avoids overtaxing businesses with more volatile revenue streams.)
Incidentally, the rules on loss-carrying have gone back and forth a lot recently. Obama’s stimulus law extended the “carryback” period, allowing Trump to attempt this at the time he did; the recent GOP tax bill eliminated the ability to carry losses backward in time for a refund of past taxes (while removing the 20-year limit on carrying losses forward); and then the CARES Act brought carrybacks back for the 2018–2020 tax years to inject some money into businesses during COVID.
Anyhow. Politically, none of this is going to help the president, but I don’t see it swaying many votes against him either.