The Reverse Button emoji is a solid coloured triangle pointing to the left. In case you missed an important part of a movie or want to watch the scene again, then you’d press this button.
The reverse button emoji was introduced in 1995 and released as part of the Unicode 11.0 standard. This emoji can be found under the symbols
category. Because the reverse button emoji has been around for quite some time, it should display correctly in the majority of operating systems.