Window control buttons become blurry when both “website color” and “compact tabs” are enabled. See the screenshot below. The issue occurs in a new default profile with the corresponding settings enabled.
New Tab (light)

Issue Tracker (light)

YouTube (dark)

For camparison, Safari with YouTube (dark)

The window control buttons should remain sharp and not appear blurred when “website color” and “compact tabs” are enabled.
Version 1.0.4 (143), WebKit 624.1.2.19.2, Mac 26.3.1 (Build 25D2128)
Tahoe (26)