iCloud backup

I deleted around 30gb off of my iCloud online. All backups are paused as I was nearly out of space. Anyhow, after deleting its showing that I cleared up only around 8gb. How is this possible? And how can it be fixed?

around a year ago I also had a similar issue where I deleted everything from iCloud and it still said that I had 200gb full on storage. It took a week or so with support to fix “the glitch”. Is there a way to prevent this from happening? It takes way too much time to get this sorted.