iCloud Drive Desktop and Documents turned off spontaneously on iMac

In Mac system preferences if an Apple ID created with secondary authentication account in which three answers for security questions , date of birth , rescue mail address and its password is set up , and this Apple ID is signed and you already had an Apple ID created with two factor authentication https://support.apple.com/en-in/HT204915

https://support.apple.com/en-us/HT204974

You sign out secondary authentication account id https://support.apple.com/en-in/HT208242

And then the two factor authentication account is signed in empty fields in the upcoming steps , iCloud Drive box has to be checked and in front of it option button will be shown , in that case desktops and documents will be shown as unchecked , you have to check the box and get it synced .

In normal working Mac desktop and documents box will not automatically get unchecked by its own .

In any case you use any anti virus , any softwares / unknown apps , vpn services uninstall all of them .

Desktops and documents box can't be automatically turn off unless you uncheck the box of it or sign out the Apple ID from system preferences , and then sign in with different Apple ID account say set up with 2FA , in the steps an option comes to set up iCloud Drive and in the last have to click on options button and then have to check the box of desktops and documents .