What it does. Scrub NASA Worldview / GIBS imagery over a box. Daily MODIS and VIIRS, HLS Landsat 30 m, and the Landsat WELD years GIBS actually has. Your browser reads the public tile service itself. NASA sees which tiles you asked for. My server sees nothing, because there is not one.
WELD is not 1984–2011. GIBS only has nine annual mosaics, dated 1 December: 1983–85, 1988–90, 1998–2000. Pick that layer and the scrubber walks those dates, not empty Junes. The desktop tool also hunts ±1 month around each anniversary for a clearer HLS 30 m scene, and can export a film.
Browser preview of Worldview Timeline. Tiles come from
gibs.earthdata.nasa.gov — a public NASA service, no account.
The Sentinel-2 change tool is a different page.