A HEIF container holding more than one HEVC-coded image, such as a burst, an animation, or the moving part of an Apple Live Photo. It uses the same container as image/heic, but the separate label tells a reader to expect a series of timed images rather than a single still.
This is the type the file command reports for Live Stickers and similar .heics files, and the value you need in an HTML file input's accept attribute if you want to receive them.
File types
.heics.hif
Also appears as
Not known to appear as any other types