In that case, are you suggesting that I leave the 8 year, 25k old belt in service? This is in a Previa, so the belts are quite removed from the normal heat exposure of an engine.
Went ahead and installed the new belts - they were supposedly mfg'ed in 2018 and 2019 in different plants. The new belts were harder than the belts I removed, not sure if that means anything.