If it stood in a dark place - air tight, then there should not be any photooxidation, that would have rendered it useless for sure.
In a dark, closed atmosphere I would say that the Naphtha itself should not degrade in a special manner ... also regarding lye there is no problem. As there is a water content, this would normally cause Germs to grow, but the lye and caustic pH will effectively kill all life. So the only concern would be a degradation of plant substances based on the aging process and this would in the worst case just render actives inactive. That any harmful substances evolve from the tea is just very unrealistic, I guess such thing was not written here. If you use the Naphtha for extracting then it would normally selectively dissolve DMT only. Therefore all the components should still not dissolve in Naphtha, except DMT. And if they degraded to other substances, then I would also say its unlikely, as a reverse reaction of molecule assembly results in more polar components mostly, not in less polar.
Just try to extract it and do a freeze precipitation - not an evaporation - and if it comes out crystaline then everything should be alright.
Just the existence of mold and decay baceteria would be bad, but that should be prevented by the harsh pH.