How do I stop the video that I have embedded from autoplaying in the KB?

It seems when I pasted embed code, it edits it out.

Starts like this:
<iframe src="sampleurl" width="560" height="315" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

After saving, looks like this:
<iframe src="sampleurl" width="560" height="315" allowfullscreen=""></iframe>