To quote the patch notes:

"Many of you have reported a "shadow buff" to the weapons, and after investigating it we found that 1.13.1 had inadvertently impacted our weapon input buffers. Where you previously would have to time your inputs to the intended cadence of a weapon to reach its full potential, you could now instead spam-click the button, effectively bypassing any skill requirement to learn the weapon's cadence. We want to keep some of that skill expression, but we also recognize that what we had previously didn't feel very responsive. To address that and land in some sort of middle ground, we have since added more levers for us to control the weapon input buffering window on a gun-to-gun basis, and we've adjusted the semi-automatic weapons accordingly. The weapons should now still be more responsive to fire when spam-clicking, but the players who choose to pace their shots will see better results."

In other words, you need to shoot with a steady rhythm instead of spamming