Giphy block: unable to select from 'Related GIFs' in Firefox

### Impacted plugin

Jetpack

### Quick summary

When using the Gutenberg Giphy block and you've selected a GIF to use, a row of related GIFs appear at the bottom. It is not currently possible to selected one of these related GIFs to use instead.

@cometgrrl adds: "The related gifs only show up in FF (I checked in Arc and Chrome), and the related gifs only show up on the front end, not in the editor in those browsers."

### Steps to reproduce

1. Create a new post and add a GIF block (type `/gif` in the editor).
2. Type a search phrase like "charlie chocolate factory".
3. Choose one of the results from the top row of thumbnails.
4. Hover over the selected GIF. Note that the 'Related GIFs' panel appears at the bottom.
5. Try to choose one of the Related GIFs.

### A clear and concise description of what you expected to happen.

Clicking on one of the Related GIFs chooses that GIF and replaces the main one shown.

Alternatively, the Related GIFs panel is not shown in the editor at all.

### What actually happened

Clicking on any of the Related GIFs did not have any effect.

### Impact

Some (< 50%)

### Available workarounds?

No but the platform is still usable

### Platform (Simple and/or Atomic)

Simple, Atomic, Self-hosted

### Logs or notes

Tested on Firefox Mac v110.

Originally reported at https://github.com/Automattic/wp-calypso/issues/74546.

Start by reproducing the Gutenberg Giphy block issue in Firefox using the listed search and selection steps, then trace the related GIF selection entry point. Done means clicking a related GIF replaces the main GIF, or the related GIFs panel is hidden in the editor.

Written by the indexing model from the issue text.