So i just switched to a S20+ about a month ago. I moved everything from my S9+ over to the new phone, no problem, including the S3. Last few days it was pairing, then unpairing itself on occasion, as well as the alarm on the watch was going off on random times, not even the times I had set on my phone. I decided to try resetting and re-pairing.
Have you tried resetting the network settings? Just a heads up, by resetting the network settings, it will remove all wi-fi and Bluetooth settings you currently have saved.
Just to clarify, have you tried wiping the cache partition on your Galaxy S20+?
You can use this link for steps on resetting the Network settings. https://www.verizon.com/support/knowledge-base-229404/
Thank you for reaching out. I would recommend reaching out to our customer service team directly at 1-800-726-7864, so they can remote into your device and see the symptoms you are experiencing. Another option would be to take your device to your local UbreakIfix so they can run diagnostics on your device and get a hands on look at the symptoms you are experiencing.