SmushCDN.com causing 4xx and 5xx errors

I’m working on a client site using Smush Pro for their CDN, and in my last audit, I’ve picked up 5xx and 4xx issues coming from the plugin.

The resource that is blocked is: https://733184.smushcdn.com/1226728/wp-content/uploads/2020/04/blog-featured-photo-1-450×450.png?lossy=1&strip=1&webp=1

One audit it will come up as a 503 Service Unavailable, then next audit its a 429 error. I’m not sure what’s going on as only 8 pages in total are pulling this error, the other pages are fine.

I’ve tried everything I can in the post itself – re-uploading, removing featured images, etc, nothing has fixed the error.

Any help would be appreciated,
Cheers!

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