jetpack CDN slow uploads/processing since update

Prior to updating the Jetpack plugin to the latest version the photon CDN version of the featured image was available instantly (they’re small, under 100kb generally), now I’m seeing a lag of around 20 minutes and the img serves a broken link until it eventually is available.

When going to the raw image URL to the cdn it returns an “unexpected 400” code.

Eventually it becomes processed and all is fine.

Could you provide guidance on debugging this or if it’s just a temporary slowdown with the 5.4 rollout (I’m on 5.3 until critical plugins catch up)?

It seems that images shouldn’t be linked from the CDN until the signal comes that they’ve been processed and are ready on the CDN.