Deleting message attachments does not lower iCloud storage usage
I have message sync turned on for iCloud. I had 4.1 GB of messages that were on iCloud. I then deleted over 2 GB of message file attachments from my conversations on my phone. However, the storage on iCloud is still the same number (4.1 GB). I did this about 2 weeks ago, so I think it should be updated by now even if it's not supposed to be immediate.
Note that after I deleted those attachments from my phone, my other device's conversations also showed these attachments to be deleted. However, iCloud storage remained the same.
Is there a way for me to directly delete message attachments from iCloud? I would expect deleting attachments on my phone to reduce iCloud storage.
iPhone 11, iOS 16