This also started for me after a Windows 10 update. Every 15 minutes would receive a new notification. Even when the system was idle; when I would come back on the notifications would be backed up and would show they had occurred at 15 minute intervals.
After some research determined the solution had to be in the Dell SupportAssist program, the SupportAssist program (this is also by Dell but is not the same), or the three Dell Data Vault processes in Task Manager. After some trial and error the solution was to uninstall the Dell SupportAssist app. After the uninstall the DDV processes in Task Manager also disappeared. The SupportAssist program is still available and works properly.
Since I regularly scan I don't believe that there was a virus involved; I am more inclined to think that somehow this has to do with a program version issue by Dell. Did find one other post where a party had the same solution. Could not find any help from Dell.
Just click the notice, which opens the Defender page, then click Add an allowed app, and choose the DDVDatacollector.exe application in "C:\Program Files\Dell\DellDataVault". The alerts will stop.
Controlled Folder Access is basically an internal firewall for your important files, so you have to whitelist known applications manually until the vendors update their programs to work within the constraints of the new ransomware protection.
Or, you could do this: (1) open up support assist program by typing "support assist" in the search bar; (2) click on settings; (3) click on privacy; and (4), and un-check the box giving permission to Dell to collect and store your usage information on servers "that may be located outside your country" so as to receive customized information from Dell and its partners.