What does Reverse Button look like on Samsung?

On Samsung it is the design shipped in One UI 8.5, shown above at full size. Older revisions are listed beneath it.

When did Samsung add Reverse Button?

Samsung first drew Reverse Button in Touchwiz 2.0, released April 26, 2013.

Samsung Electronics has shipped 26 versions of Reverse Button. Each is dated, so you can see when the design changed.

Samsung Experience 9.0

Samsung shipped a new design for Reverse Button in Experience 9.0, released February 11, 2018. The previous design is shown beside it.

✳ marks a release that redrew this emoji. The rest re-shipped the design unchanged.

What does Reverse Button look like on Samsung?: On Samsung it is the design shipped in One UI 8.5, shown above at full size. Older revisions are listed beneath it.
When did Samsung add Reverse Button?: Samsung first drew Reverse Button in Touchwiz 2.0, released April 26, 2013.
How many times has Samsung redrawn Reverse Button?: Samsung Electronics has shipped 26 versions of Reverse Button. Each is dated, so you can see when the design changed.