https://www.supremecourt.gov/opinions/23pdf/23-108_8n5a.pdf is I believe what they're referencing. And it definitely muddied the water.
[1] https://en.m.wikipedia.org/wiki/McDonnell_v._United_States
The only thing the Supreme Court decided in that case was whether that specific statute encompasses a gratuity theory. That’s illegal for federal officials under a different statute that was not invoked in this case.