Help Needed with Voltage Drop in Ring Wired Doorbell Pro (Video Doorbell Pro 2)

I recently installed Ring Wired Doorbell Pro (Video Doorbell Pro 2) + Pro Power Kit v3 with an existing Indoor Mechanical Chime. The Device Health shows that the Power Output is "Level 3," indicating that the transformer is underpowered. The doorbell seems to be working most of the time, or at least 50% of the time. I found a doorbell transformer in my garage. It is connected to three outputs, one of which is for the doorbell chime. I noticed a significant voltage drop and need some advice on how to address it. - Transformer output voltage without load: 18.7V- Transformer output voltage with load: 17V  - Transformer output voltage only with DoorBell load (After removing the other two output wires) : 17:4V - Voltage at the doorbell chime: 15.6V The voltage drop seems higher than expected, and I'm not sure what's causing it. Does anyone have a similar issue? Are there any tests or steps I can take to diagnose and fix the issue? Should I upgrade to a 24V transformer to compensate for the voltage drop?