Hello...I am new to the Silverado world and have recently purchased a 2019 Silverado 1500 Z71 Trail Boss. I am having the same issues as you all have mentioned. This article about a recall for 2014-2018 models sounds a whole lot like the same issue. I'm headed to the dealership in a few days...maybe we can find a fix!
https://www.cnbc.com/2019/09/11/gm-recalls-over-3point4-million-pickups-and-suvs-to-fix-brake-issues.html