Discovery is airing tonight here on CBS, 10pm EST. I have Comcast cable, and a little after 9pm I looked at my guide, and Discovery was scheduled to record. I never set it, and the option to cancel the recording wasn't there at all.
Did CBS strike some sort of deal with Comcast to force the recording of Discovery to increase interest?
Discovery did air on CBS back in 2017. If at that time you set your DVR to record the series (even though only one episode was on CBS) it may have remembered so it is continuing to record the series