can i use aluminum pot covered with teflon to brew tisane/tea?

Eeew. To the aluminum and the teflon.

Just get an inexpensive stainless steel pot. Then besides commercial teas and tissanes, you can also boil and simmer herbs, roots, barks and flowers to make your own traditional tissanes or medicinal teas. You can keep them warm or brewing for hours on the stove over a small flame or even on a small stand with a candle or oil based wick candle.

do those make the tea taste bad? or is it the health concern?

we have ss but it is a little too big for just a cup of water ^^’

Health, aesthetics, potential leaching of the coating at high temperature, cost, you name it.

If you have one of those ubiquitous (around here anyway) restaurant supply stores near you, you can buy almost any size and shape of ss tea pot for fairly cheap, a couple of bucks. I have a larger one that I use to steep herbal brews and a small 10oz one that I throw in my bag for when I’m traveling or visiting a friend for the weekend. I put a weekend’s worth of leaves in a plastic baggie and stuff it inside the pot, then I can always have a decent cup or two of tea in the morning or afternoon.