Insert activate (power button) green instead of blue

Does anyone know what it means when the insert activate (looks like an power switch, usually blue used to activate / deactivate an insert) changes colour to green signify? I gathered it's possibly got something to do with dropout protection, but information on this feature seems sketchy.

It seems that in FabFilter Pro-Q2, when I switch my "dropout protection" to "medium", the activate button tus green. When it does this, the graphical EQ doesn't update but the sound is somehow unaffected (!?)

Can someone explain the significance or point me to an manual page?

Thanks!

Tian