[thiht]

You should not use boiling water for tea as it will burn the leaves. It’s good for herbal tea and infusions but not for tea. As a rule of thumb, you should never go over 80°C for green tea (preferably 75°C), or 90°C for black tea.

If the instructions on your tea say 100°C, it’s either not tea, or very bad quality « leaves » (more like scraps)

[simonsquiff]

Black tea is what most of us kettle owning Brits drink, and apparently 100c is what you want. In fact it's a selling point of some boiling water taps that do true 100c rather than 98c of competitors

https://www.billi-uk.com/perfect-temperature-hot-cold-drinks...

[TeMPOraL]

I don't know what you should or should not do, but I can tell you this: I drink black tea a lot, and I can easily tell whether one was made with water taken straight from the electric kettle after it automatically disengages, vs. one minute later, vs. from "hot" water from a coffee machine or a watercooler. The first one - straight after it finished boiling - is what tastes best to me.