Marco Russo clues us in on a bug:
In mid-January 2026, many Power BI Desktop users began noticing a strange visual regression: several icons in the interface—including the Data, Model, and DAX icons—appeared as solid black shapes instead of their normal outlines. The issue appeared suddenly, even on machines where Power BI Desktop had not been updated. Because it happened the same week that Power BI Desktop January 2026 was released, this led to understandable confusion.
The root cause was not Power BI Desktop itself but an unexpected regression in the WebView2 runtime, one of the external dependencies used to render parts of the UI. Microsoft confirmed the issue and is preparing an official fix.
Marco does have a temporary fix that works until Microsoft has the official fix in place.