DHS routinely tests TSA and they always fail spectacularly. This was just the first one on Google. You can easily find many more, this is widely reported on.
You realized there has been a complete overhaul in equipment since 2017?
In your citation: In the public hearing today on Capitol Hill, members pushed for the full implementation of a program using new scanning equipment that creates a 3-D image of bags, giving screeners better ability to spot possibly dangerous items
Those new scanners are in 255 of the nations 432 airports
Every time they've tested it, the testers were able to get 70-80% of their weapons past the TSA; which, yes, includes guns.
I don't know precisely how they achieved that, but they certainly did.