Hi TLM_1978,
Thank you for posting in Apple Support Communities! Let's take a look at your notification settings. If you go to Settings > Notifications > Messages, is Badges enabled?
Check out: Use notifications on your iPhone or iPad - Apple Support
If enabled, has your iPhone been restarted since noticing that badge was missing?
To restart:
1. Press and hold either volume button and the side button until the power off slider appears.
2. Drag the slider and wait about 30 seconds.
3. Press and hold the side button until the Apple logo appears to power it back on. Once back on, test to see if this continues.
Check out: Restart your iPhone - Apple Support
Hope that helps!