RG-W08: Too many watch entries were waiting, so the oldest was dropped
Your iPhone had more watch entries waiting to be saved than it keeps, so the oldest waiting entry was dropped. This is unlikely in normal use.
What to do
This looks like a problem in the app, not something you can fix in Settings. Please email support@cadentiahealth.com, mention code RG-W08, and paste the text from Copy status report in Regularity’s Status screen. The report contains app and system versions and status identifiers only. It never contains your entries or reminder times.