Suffice to say, if there were meaningful risks from drinking normal amounts of coffee, it would be known by now. Its main drawback is that it makes people nervous and jittery if taken in excess.
One of the other major ones is that it can aggravate stomach problems like gastritis since both coffee (even decaf) and caffeine are said to stimulate stomach acid production.
Sleep problems as well and migraines.
I believe caffeine is both a treatment for, and a cause of headaches. [1] Excedrin for instance is a migraine treatment which includes Tylenol and caffeine.
Reason it’s a treatment is helping absorption typically, but also, a lot of people’s headaches are from withdrawal so it helps in the way drinking a beer helps a hangover.