Verify your subscription is actually cancelled by following the steps in the support document linked below.
click here ➜ If you want to cancel a subscription from Apple - Apple Support
If it is cancelled, the explain where you are seeing these charges and what they appear as.
If they appear directly as "Fox Nation" or something else other than "Apple.com/bill", then Apple is not charging you for it, or not through the Apple ID you are currently logged in with, as such either you are being charged on another Apple ID or you started that subscription on a different platform or directly at the fox website in which case you need to cancel it through there too.
https://help.fox.com/s/article/FOX-Nation-How-do-I-cancel-my-FOX-Nation-streaming-service