Even though Ethereum blockchain is the second most popular in the cryptocurrency industry, it actually has some problems regarding scalability. (Scalability refers to the number of transactions that can be processed by blockchain per second.)
As I mentioned before, Ethereum is only able to process 15 transactions per second. In the early days of the project this was not a problem, because not many people used it. However, because Ethereum has become more popular, it has become the biggest problem facing the face of the blockchain Ethereum.