Seems like any program that checks or verify's other programs such as an anti-virus or backup program or cloud program puts a green check mark to let the user know that that program, document or folder has been given the 'once over' an either is verified,
deemed to be good or saved. Have never seen this type thing till W10 rolled out.
I don't use Norton or any AV other than Defender, nor do I use any 'Cloud' service, nor do I use any M$ back-up/restore function, but still have gotten those check marks (from time to time) so there's no telling what or how many programs (called apps these
days which I think is a joke it's a program folks not a smart phone deal) trigger this.
The stand out thing is it is harmless (alarming at first sight not knowing what the heck it is) a desktop refresh removes them, but if you're a power user like myself you're always wanting to know what the heck is going on at all times.