Facebook Team is working on this issue - here's the current bug report where they're providing updates: https://developers.facebook.com/support/bugs/272250004017849/ We will continue to update the status of this issue whenever Facebook Team provide updates.
Posted Jul 01, 2020 - 13:01 UTC
Identified
We've received reports of GIFs not being sent to the bot users. We've confirmed this is a Facebook issue, and will provide updates as soon as they have more information on it. Here you can see the original bug report to the Facebook Team: https://developers.facebook.com/support/bugs/1212783012393864/