Found the solution to my issue: It must be a bug or something.
I have a relatively new iPhone Pro 14. The Reminders app was not providing reminders. An important/odd clue was that the Reminders app was not even shown under (settings-->notifications), despite being installed on the phone.
Solution: I was trying to do all my reminders via Siri. Once, I manually went in and tried to type a reminder, a prompt came up asking me if I would allow the app to provide reminders. Once I allowed this, the problem was fixed. It's like the initial app installation does not complete until you manually try to create a reminder for the 1st time (vs. using the reminders exclusively through Siri).