WowAce

What version of Grid2  are you using (Version is displayed in General/About Tab) ?
3.4.2

What game client version, classic or retail, windows or mac and language are you using ?
Retail, windows, English

What steps will reproduce the problem? 

  
Did you try having Grid2 as the only enabled addon and everything else disabled?
no, but disabling the addon and having blizzards own raid frames fixes the issue (i Disabled the glow overlay in CVars) (raidFramesIndicatorOverlay & raidFramesDisplayIndicatorType)

Was it working in a previous version? If yes, which was the last good one?
I just returned from a long hiatus, so i cant tell. Last time was shadowlands, where the blizzard dispell overlay was not implemented.

Do you have an error log of what happened? If you don't see any errors, make sure that error reporting is enabled (`/console scriptErrors 1`) or install [BugSack](https://mods.curse.com/addons/wow/BugSack).

Please provide any additional information below.

To remove the dispel overlay, goto indicators -> privateaurasdispell and click on the red X icon in the indicators settings (panel to the right)  to remove the indicator.

But if you delete the indicator you will not see the boss dispels, but you can enable the "Hide for normal dispellable debuffs" option, and  the overlay will not be displayed for normal dispels.