Vignette" becomes VIDEO HUM deffect
I've used the VIGNETTE on Lumetri Color in a delivery. The TV technical department called it a VIDEO HUM , had to remove it clip by clip.
Johan Malmsten commented
If I interpreted the description correctly... Sounds like it creates broadcast illegal values. Letting color values go outside the legal values can in some broadcasts bleed out to the sound channel. Creating humming noises audible for the viewer...
This is a strange quirk of old analogue broadcasts and tv sets and sadly it is still to this day a part of requirements that must be met by a lot of broadcasters. Because they have to be backwards compatible with granddads old CRT black and white TV set with the same signal used for their UHD 60hz broadcasts. As a technical feat of engineering it's mind boggöing that they can juggle such vastly different systems but it requires some archaic requirements from the source files.
So. If that's indeed what they are referring to. Adobe might have a solution/workaround. already.
In the export setup (in both media encoder and premiere). You can apply filters and overlays and such to the whole export. In there there should already be a tool to clamp signals to be broadcast friendly. That way you could use whatever effects you want on the timeline but the resulting files signal levels would still not exceed what the broadcaster allows.
If possible, do a test clip with similar effects and content and send it to your broadcaster with and without the signal clamping and ask if that is fixing the issue. These exports are also important to learn what the colors look like to your eyes.
So it could be that it's not a "bug" exactly... Premiere lets you go outside the archaic rules because it don't assume what you are going to play the result on. It's up to the end user to know what the limits are for the clients needs, sadly... :)