"In 2014 a 56-year-old-man experienced some health complications after taking too tea. The man encountered kidney problems after taking 16 glasses of tea per day. In this regard, too much tea leads to a higher concentration of oxalate (mainly found in black tea) and this can cause renal failure. So, you should control your tea drinking habit if you want to avoid some health complications later in life."

Source: https://topictea.com/blogs/tea-blog/30-interesting-facts-about-tea/