Food for thought
We make so-called "sun tea" all the time. In fact, we often make it on the kitchen counter at night and it works identically as far as we can tell, although it may take a little longer. Your mention of a "few minutes" is pretty quick. We usually let it sit for a minimum of 4 hours.
You may want to try the regular type of tea bag (vs. the "cold brew") and see if it matters. We have never used anything but the regular type.
Thanks for sharing.