I'm a network engineer and I think this is the first time I've ever heard the claim that "routers give TCP priority" (ICMP is often de-prioritized but that's on

I'm a network engineer and I think this is the first time I've ever heard the claim that "routers give TCP priority" (ICMP is often de-prioritized but that's on the control plane). Exactly which routers are alleged to be doing this?