I'd suspect that this is a widespread(-ish) problem. When you check your bag, it leaves your control and is handed off between TSA and your airline just enough

I'd suspect that this is a widespread(-ish) problem. When you check your bag, it leaves your control and is handed off between TSA and your airline just enough that they both have plausible deniability when something goes missing. If something goes missing, they'll be happy to start pointing fingers at each other - trust me.