Some time ago I was at my local exotic woods supplier and came across a sheet .020" of what was labeled Ebony Gabon. I have purchased this species in the past in 2"x2"×20" "turning blanks" It has always been much darker. This stuff looks much like black and white ebony to me. Regardless, it's very cool looking wood.
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Apparently it can have some brown streaks in it, but yours is mostly brown with black streaks?
It's not a good picture for evaluating grain quality.

All the Gaboon I ever seen was almost black with some whiteish streaks in it.

Here is a pic of some e-drums I wrapped with it
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That looks a lot like some black limba that I have.
Dave.

https://www.wood-database.com/gaboon-ebony/

Ya, its definitely black limba...

I have a piece that looks just like yours. I can post a picture for comparison if you like.
Dave.

The outer sap area of gabon ebony is very creamy white. it is rarely seen because they cut it off before it ever gets here. It generally doesn't have streaks, but the black will sometime invade the sap and vice versa.

I think you already figured out what you have is limba.

BigJim