icloud backup copy too big vs reality?

iCloud 50gb-version notifies me it is almost full.

When you see the summary screen it shows a backup of 27,8gb (see photo 1), when you click on the detail it shows 3,8gb for my phone (see photo 2) Somehow I deel to have 24gb worth of ‘ghost backups’

My question is: How can this difference be explained? Can i get rid of the 24gb surplus?

I looked around on this forum and the internet, I even contacted Apple but I didn’t gert a solution yet.

Maybe someone here can help me? Thanks in advance!