[capt_slow]

I was poking around my engine bay and noticed my coolant expansion tank was near the low mark, even with a warm driven engine. I looked though my records and realized that

Dec 2019: Last dealer service, expansion tank full (overfilled beyond top half of the tank)
Nov 2020: Coolant level seemed normal on cold engine, level just at the high mark.
Today: Coolant level at low mark warm or cold engine

So in about a year, the coolant level dropped from the overfilled to low, and it dropped from normal to low in less than a month. The last time I touched the system was during my PH test in late October, but all I did was extract, measure, and return to tank.

I inspected all coolant hoses, radiators, and connections, no visible signs of leaks. The dealer did the EGR cooler recall back in Sept 2019 and it checked out fine. I dont have any other symptoms of a EGR cooler issue, no faults, no abnormal smells. What are the chances the EGR cooler is causing the leak?