iCloud Backup was introduced in iOS 5, released in 2011. It escrows either message plaintext or device secret keys (depending on OS version and configuration) to Apple, encrypted with Apple keys (non-e2e) and readable to Apple (and the FBI and others, some of whom access the data without probable cause or a warrant under FAA Section 702).
WhatsApp backup backs up chat plaintext to cloud services (I think Google is the default), also non-e2e and readable to the cloud storage service (who often shares it with government snoops without a search warrant, also under FAA Section 702). They added an e2e option late last year but it doesn't matter if you turn it on because none of the people you chat with are likely to have it enabled (so all of your chats will be backed up in plaintext from the other end).