Does a tea candle warmer change the taste of tea?

I’ve been using a cast iron tea kettle to make myself a morning’s worth of tea. I drink mostly green, black, and oolong. I’ve been keeping the kettle on a cast iron warmer which uses a tea candle to keep the kettle warm for an hour or longer. I’ve been reading that doing this may continue to “cook the tea” changing the taste, color, and overall complexity of the tea. Is that true?