Hello Lior79,
Thanks for the post in Apple Support Communities. I understand you have a question about backing up your WhatsApp history.
I found this information in a resource published by WhatsApp that should answer your question. This is from their article titled WhatsApp FAQ - Restoring your chat history:
"Requirements
- You must be signed in with your Apple ID that you use to access iCloud.
- You must have iOS 7 or later.
- For iOS 8 and later: iCloud Drive must be turned on. You can check this by going to iPhone Settings > tap your name > iCloud, then making sure iCloud Drive is turned on.
- For iOS 7: Documents & Data must be turned on. You can check this by going to iPhone Settings > iCloud > Documents & Data, then making sure Documents & Data is turned on.
- There must be enough free space on both your iCloud and iPhone."
Based on this, you would need sufficient space on both the iPhone and in iCloud to complete the process. Requirements for backing up third-party apps are ultimately going to vary by the app, and based on the information above, this looks normal for WhatsApp. You can always get in touch with WhatsApp support using the guidance here: How to contact an app developer
I hope I've answered your question.
Take care.
