What did you even need to pause for?

It wasn’t officially announced but it’s known that it was being worked on and got shelved. Some devs wanted to use the Unreal Engine since Source 2 (at the time) wasn’t up to par to what they wanted. Without everyone on an agreement on what to do, they moved onto other projects since Valve is a “work on what you want” environment. I believe there was a massive Valve data leak years ago and some possible L4D3 assets might have been leaked, but I think it was just level design concepts built in Source 2.

Also Left 4 Dead 3.