There was always an Overton Window and it has always been moving around. And often people (usually older people) do not like when they have opinions which are being excluded from the Overton Window when previously they were acceptable.
I find that it is best to be specific about what should be in and what should not be in the Overton Window rather than being general.
Why? Discussions of "cancel culture" seems to me to pretend to be meta discussions on whether the Overton Window should exist, but usually they are actually about whether certain topics should be within it. I find that this is a bit of a deception and used to disavow that you are unhappy with the current position of the Overton Window with regards to very specific issues, usually because if they discussed the specifics of their concern, it would actually fall outside of most people's Overton Window - thus the need to argue the meta route.