I don't know for sure how Paramount+ assigns your local station, but there's a good chance it goes by the location of the IP number your ISP assigns to your account.
If your internet provider assigns or changes your IP number to one attached to one of its servers located in a different area, that could change the local stations you are provided.
You can use an IP info website like the ones listed below to see where the IP number assigned by your internet provider indicates you are located. If this doesn't represent your actual area, you can contact your internet provider and ask to be reassigned an IP in your area.
Some IP info websites:
https://www.iplocation.net/
https://www.iplocation.com/
https://tools.keycdn.com/geo
https://www.ipfingerprints.com/
A web search for "IP Location" can find many more.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X