Describe the solution you'd like
the current implementation of "inventory highlighting" appears to "lowlight" all slots that don't contain the search term.
this is especially pointless when using a resource pack with a dark themed inventory.
could we have it reversed so the slots containing items with the search-term get highlighted instead?
also a good option would be a simple custom overlay option for these slots.

Additional context
https://imgur.com/a/GsrDyl1

@superon Roughly Searchable has a setting, "Darken Background" (accessible from the REI plugin settings), which dims items that don't match. It's not on by default though.

Can someone here link a resource pack that I can use for testing that is dark

huh, well i did find that option but for whatever reason it didn't work like the pic you included for me:/ maybe it did something but was so slight i didn't notice.. i just assumed it was darkening the "background" (as in the slot behind the items, which obviously doesn't help with a dark inventory)..
i'd changed the scale of the items to be almost non existent and that was working reasonably well, will load up and grab images..

darkening the "background" sounds like default behaviour to me, perhaps that's just me of course ... also tried this without a resource pack an experience the same thing (images don't darken).
so at this point i feel pretty certain there's another option i'm missing.

this is what i've been recently looking at:
https://www.curseforge.com/minecraft/texture-packs/conquest_

that looks awesome, v much a fan of green too so that fits my theme :) looking forward to this update <3

Thanks for your suggestions, it will now look like this in the next updates.