* Pushing with docker is limited to images that have layers of maximum size 500MB. Refer to maximum request body sizes in your Workers plan.
* To circumvent that limitation, you can manually add the layer and the manifest into the R2 bucket or use a client that is able to chunk uploads in sizes less than 500MB (or the limit that you have in your Workers plan).
It does mention that it's limited to 500MB per layer.
For some people's use case that limitation might not be a big deal, but for others that's a dealbreaker.