My survival world is only about 6 months old, and was kess than 150mb until recently. I didn't notice when, but my suze after syncing shows 280mb now, but the.cloud size is showing as 3.7gb after deleting local saves. My son's small world won't even sync, and is unplayable now.
I had 2 of my son’s worlds in the unplayable state (that we were just going to delete) and my main world with the failed due to quota error. The smaller of the unplayable worlds I was able to sync and ultimately delete successfully. The larger would not sync, but I was able to delete it from the main menu by choosing multi select and deleting it. My main world (290gb) still gets the unable to sync due to quota error.