Let's take the following company. The current ETH Balance is 268,691.327038426 Ether:
But API response 268698327038426745609145:
As you can see API response does't contain floating point so the balance value is very big.
Is it bug?
it isn't a bug the balance is returned in weis not in The Ethers.
chek one of many conversion tools: https://etherconverter.online/
268705.32703842675 Ether = 268705327038426745609145 wei
the "," is used to separate three digits (look at the amount in $).