Windows10 Taskbar Preview thumbnails appear at wrong size when using 125% or 150% display scaling

Because taskbar thumbnails are correct at 100% but distorted at 125% or 150%, this points to DPI scaling or graphics rendering, not damaged application windows. Set the display to its Recommended resolution and scale, sign out, and sign back in; some interface elements recalculate only in a new session. With multiple monitors, test one monitor, then apply the same scale to every display before reconnecting them. Install Windows updates and the manufacturer’s graphics driver. Restart Windows Explorer from Task Manager and remove taskbar customization or shell-modification utilities. Do not change unsupported registry values for thumbnail dimensions while diagnosing. Microsoft supports changing scale under Settings > System > Display but does not document cropped previews as expected behavior. If it persists with default settings and no customization software, reproduce it, press Windows+F, and submit Feedback Hub diagnostics with the Windows build, GPU driver, resolution, scale, and screenshots.