Sure! More than 400mg is not recommended and may lead to overdose symptoms. (Less for teenagers and pregnant women.) With strong coffee, 8 cups can easily total more than 1000mg of caffeine. Mild over consumption of caffeine causes known problems like dizziness, anxiety, and headaches. More severe overdose is things like irregular heartbeat and vomiting.
https://www.healthline.com/health/caffeine-overdose
The other problem with large coffee intake is that the acidity of coffee long term can be bad for your stomach and lead to or contribute to heartburn and ulcers.
https://www.manhattangastroenterology.com/coffee-digestion/
Those two links are just from super quick first Google result searches, but these downsides of caffeine & coffee are pretty well known.
Possibly unrelated tangent, but I read once that 70 cups of coffee is expected to be in the vicinity of a fatal overdose. First Google result, this article even suggests maybe ~25 cups: https://www.vice.com/en_us/article/exmwka/how-much-caffeine-...