Wait For Good - Mechanic explained
Mainly aimed at speedruns but also very fun to abuse in normal gameplay.
Some more info: ANYTHING that causes you to stop shooting even if the button is held causes the Wait for good proc to stop, An example with rainbow would be Right-clicking causes a small pause, Using any of your secondaries (Cleave/Blossom/Grenades) sometimes enemies knocking Knocking you back 'can' cause it.
This is specific to only injectors, You can see the list of them in the Armory section in-game or just the Wiki.