I have a 2021 silverado with about 31,000 miles on it. 5.3 V8 with the 8 speed transmission.
I know these trucks have issues with DFM AFM and lifter issues. Although this truck is not equipped with this option(because of the chip shortage) but I believe the lifters are still the same type.
I do not think it's a lifter tick. I think it may be from the "high pressure fuel system". Not sure just seen that somewhere gm put out a TSB about the fuel system making noise.
I attached a video of the noise. It sounds like a clock ticking and is kind of a background noise.