If, by chance, the changes are not being made in conjunction with the track changes feature, at least in word you can use the advanced find option [ALT+H,FD,A], format button, font option, to find something that is a specific color. You need put nothing in the find string, but need to set the color you're looking for. If you don't set the specific font or any of the other attributes than color, it's only searching for any text in any font in any size that is the color specified.
If you want to get heavy-duty into advanced find in the Office Suite programs I'd suggest heading over to the Microsoft Office Accessibility Discussion Group and going crazy with questions there.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
Always remember others may hate you but those who hate you don't win unless you hate them. And then you destroy yourself.
~ Richard M. Nixon