What does Cross Mark Button look like on Facebook?

On Facebook it is the design shipped in 16.0, shown above at full size. Older revisions are listed beneath it.

When did Facebook add Cross Mark Button?

Facebook first drew Cross Mark Button in 1.0, released January 31, 2014.

Meta Platforms, Inc. has shipped 13 versions of Cross Mark Button. Each is dated, so you can see when the design changed.

Facebook 3.0

Facebook shipped a new design for Cross Mark Button in 3.0, released December 2, 2018. The previous design is shown beside it.

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

What does Cross Mark Button look like on Facebook?: On Facebook it is the design shipped in 16.0, shown above at full size. Older revisions are listed beneath it.
When did Facebook add Cross Mark Button?: Facebook first drew Cross Mark Button in 1.0, released January 31, 2014.
How many times has Facebook redrawn Cross Mark Button?: Meta Platforms, Inc. has shipped 13 versions of Cross Mark Button. Each is dated, so you can see when the design changed.