Its something that is still very well a concern, anchor outputs or not

In this scenario though, fees didn't really go up too much. There's a pretty low floor where low valued transactions can still get in. If we get into scenarios where everyone is paying a lot for fees then its more of a concern for a mass exit attack.

However, if an attacker wanted to, now would be a good time for them to continue to push up the mempool even more. An attacker can wait for high fees to occur naturally or do it themselves.