Fuel contamination? Any idea

Is that just 2 layers in the sample? Is there oxyginated fuel involved here?
Ive seen oxyginated fuel clean out a gas tank that at one time sat long enough to evaporate all the old fuel out of it.When the varnish delaminates from the tank walls,it
comes off in sheets and sloshes around in the tank as semi-floating mats.When the lighter components move out they are a gooey sticky mess, and dark colored.
Pour some accetone into that sample.If Im right, it will begin to dissolve that dark colored stuff.
Oh yeah its hard clean it all out. Buy several filters, and keep the tools in the car, for 6 months to a year.That stuff gets into the fuel lines too and may clog them up from time to time ,requiring pressurized air from the carb end to blow back into the tank.I removed the inlet sock to facilitate this, and put a new one on. The old one was gummy.