Ananya, Priya has it exactly, and it's the single most important thing to internalise here.
A genoise is a foam cake. Its entire structure is aerated egg - the flour is almost incidental to the lift. Remove the egg and you haven't removed an ingredient, you've removed the structural system. Anything dropped into that gap is compensating for the wrong thing. That's why results go dense or gummy, and the aftertaste you're detecting is usually the chemical leavening working overtime to do a job it was never designed to do alone.
What works: stop substituting. Start from a formulation engineered around a different structure entirely - emulsion plus chemical leavening, with fat, liquid and acid balanced for a fine moist crumb rather than a foam. Get the acid and leavening in proportion and the aftertaste disappears, because nothing is overdosed.
This is a big part of why we teach eggless as a full parallel curriculum, not a substitutions module. In the Indian market it isn't a niche accommodation - for many bakers it's the majority of the order book, and it deserves the same standard as the classical French work.
