light knocking noise from under mid section

What is your question?

Consistent light knock at about 100 rpm coming from under vehicle mid section. Tends to go away as I accelerate (maybe I cant hear it due to vehicle noise).

What makes this problem better or worse?

Just noticed it this morning. 38,500 miles on odometer.

How long has your 2017 Chevrolet Tahoe had this problem?

Just noticed due to tranquil morning.