Why does a bright pointer have a halo on my mini-LED display?

A bright pointer against a dark background can reveal the display’s local-dimming zones. Each backlight zone covers many image pixels, so lighting the pointer can also illuminate the area around it. This is commonly called blooming or a halo effect.

Higher brightness can make the effect more noticeable. Compare the same dark scene at a lower brightness and with brightness upscaling disabled. If the surrounding glow becomes less conspicuous, that comparison helps you choose a comfortable setting. It does not prove the cause of every cursor artifact.

BetterDisplay cannot make the panel’s physical backlight zones smaller. If your monitor offers its own local-dimming setting, compare the available modes using the monitor’s instructions. Do not assume that every display exposes such a setting or that disabling it preserves the same contrast.

Apple’s explanation of mini-LED local dimming describes why a backlight zone larger than an LCD pixel can produce blooming. A pointer that merely stays bright while the desktop is dimmed is a different issue. See software dimming and the cursor.