Issue with YouTube embeds

Having a very strange and intermittent issue with using the YouTube embed block on my website, which uses the Twenty Twenty theme. Sometimes the embed works, and sometimes it doesn’t.

Here’s a page where the YouTube embed is not working: https://thepalmermethod.com/why-i-dont-use-fountain-pens/

And here’s a page where it is working: https://thepalmermethod.com/casual-writing-and-why-i-keep-a-journal/

Here’s a screenshot of the issue: https://snipboard.io/zn2eNU.jpg

Things I’ve tried so far:

1. Deactivate all plugins & cleared all caches -> NO CHANGE
2. Remove all custom CSS from the Customize settings & clear caches -> NO CHANGE (I haven’t customized any of the theme files)
3. View the page in an incognito tab with Ad blocker turned off – NO CHANGE
4. Change themes to Twenty Nineteen – ISSUE RESOLVES

So something is going on with the Twenty Twenty theme and YouTube embeds. Weird because there are no javascript errors in the console and it’s not happening for all of my YouTube embeds. When I edit the page, the embed shows up just fine in the block editor. I should also note that sometimes the video will embed, then I’ll come back to the page a few days later and the embed is broken.

Any ideas on how to debug this are appreciated.

The page I need help with: [log in to see the link]