A thumbnail can appear warmer, darker, or more saturated on another display. Screen settings, ambient light, and image handling all affect what a reviewer sees.
Establish a reference view
Review your image on a screen with stable brightness and without a strong color filter. Then inspect it on another ordinary device. The goal is to catch major readability problems, not to force every screen to look identical.
Focus on robust relationships
Check whether the subject separates from the background and whether text remains readable when the display is dimmer. A design that depends on two nearly identical shades may be fragile even if it looks elegant on your editing monitor.
Preserve the export
Keep the source project and final file so you can compare them if a platform preview looks different. Avoid compensating for one unusual screen by making the image extreme everywhere else. When color accuracy is essential to the subject, use an appropriate color-managed workflow and verify the actual delivered file.