Bagged tea comes out weak
The same tea is thin from a bag and fine loose, or it turns bitter before it turns strong.
Likely cause
The bag slows extraction rather than reducing it. The caffeine rate constant is about 29 per cent lower than for loose leaf, so a four-minute steep gets less out.
Try this now
Dunk the bag steadily for the first thirty seconds. If the cup improves, the bag was the limit.
What to change
Agitate it, cover the cup, and choose a larger or pyramid bag: leaf that can move extracts faster. Steeping longer is the wrong lever.
The reason behind it
Dunk it. Longer does not fix weak, it just adds bitter.