The Big Diomede and Little Diomede are islands in the middle of the Bering Strait. Although only 4 km apart, they belong to different countries and have a 21-hours time zone difference.
Flat-Earthers noticed the number of polar days is different on both islands during the summer solstice & they used it to discredit science. In reality, the islands are very close to the Arctic circle, & during the June solstice, the sun’s path is almost parallel to the horizon. A tiny change in latitude or height can result in a large change in sunrise & sunset times.
The difference in sunset and sunrise times during the summer solstice in both islands will not matter much in the grand scheme. Considering the sun’s path, the numbers are just technicalities during these times. They will not affect the lives of the inhabitants of both islands.
References
- Little Diomede Island, Alaska, USA — Sunrise, Sunset, and Daylength, June 2021 – timeanddate
- Big Diomede Island, Russia — Sunrise, Sunset, and Daylength, June 2021 – timeanddate
- Diomede Islands – Wikipedia