WhatsApp Backup saved under iCloud Drive on iPhone

A week ago I successfully transferred from my android phone to an iPhone 13 Pro Max using the iOS transfer app. Now, on my new device, I am having a problem backing up my WhatsApp chats from the app to my icloud: After each successful backup, when I check the free local storage on my iPhone, I see an entry for the iCloud drive about the size of my Whatsapp data (12.53 GB). Unfortunately, this is in addition to the storage used by the Whatsapp app itself. So basically, after a backup, twice as much free space on my phone is being used by WhatsApp. None of my friends seem to be experiencing this behaviour. Is this normal? I have updated to the latest version of the app.

And I have a second question: what do you suggest: backing up the chats through the app or as part of my device backup? I currently do both, which uses twice as much cloud storage as I need. I thought it was better to be safe than sorry, but could this be problematic when restoring a device's data in case of a new setup due to duplicate data? Note that this is not related to the first issue.