Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Different apps -- I suspect you're talking about The Roku Channel, but you never specified -- have different programming available. Apps such as the Roku Channel get most of their content from other sources, such as FilmRise and other similar services. For that programming, Roku Channel is basically an aggregator. Other content, Roku may actually negotiate to carry the rights.
Whichever situation it is, there is a negotiation between a service (FilmRise, etc) and a content owner -- for Sanford & Son, I think it's either Nelson Entertainment or Warner Media, but I'm not sure -- for the rights to stream the show.
It's frustrating when shows you want to watch are suddenly not available. The good news is that companies usually have another service lined up in case an agreement can't be reached. Based on what @ric46ace said, there are alternative ways of watching it.
DBDukes https://www.dbdukes.com/Roku Ultra (4660) Roku Streambar (9102) Roku Streaming Stick+ (3810)