In the upcoming draft of COLR spec, PaintSweepGradient's startAngle/endAngle are encoded with a +1.0 bias to allow for representation of a full +360° positive angle. Normal F2Dot14-fraction-of-half-circle angles can only represent angles between -360 <= angle < +360
This is a breaking change and will need to be coordinated with rendering implementations (at least FreeType/Skia).