A while ago we had a discussion about tannins where I stated too hot steeping could cause astringency and was quickly correct that pH is the cause, not temps.
I was reading an article in the September 2016 BYO Be your own beer judge/Decode your homebrew like a pro by Brad Smith of BeerSmith fame. It states “For extract brewers, tannins come from steeping grains in water that is too hot or steeping with too much water”. It goes on to say “For all-grain brewers the most common problem is getting the grain bed too hot during the sparge”. For both it states the temp should be no hotter than 168°.
It does go on to say “You can also extract tannins from an elevated pH (above 6.0), which can happen at the end of the runnings, though this is not very common for homebrew scale systems…”.
I think our original discussion started from the instructions in a kit saying to steep in a very hot temp.