"overly casual" advice regarding lemon juice is probably sufficient.
its not rocket science, its just acidifying water.
if you use too little, it won't matter much, because some extract without any acid.
if you do too much, it won't matter much, you will just have to add more base (unless you are doing manske in which case it might cause an issue, but nothing that can't be fixed with base precip)
EDIT:
if you are planning to do an extraction, it would probably be best to boil and acidify, just to make sure you get all the actives, as you are going to be isolating and purifying the alkaloids anyways..
for tea though, acid is not needed, and even discouraged (though not for any reasons relating to "toxicity" )
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