Hi Erdi, 

Welcome to Box Community and glad to help! 

We have corrected your account storage on your account. To verify this, log in to box.com> Account Settings> Used Storage. 

Let us know in this forum if you'll get this issue again. https://support.box.com/hc/en-us/articles/360043695334-Storage-Usage-Or-File-Count-In-My-Account-Is-Incorrect

Thanks for posting!