When there is a significant volume of transactions on the Ethereum network, gas can become expensive. There is a limit on how many transactions can be included in each new block that is added to the Ethereum blockchain. Miners are rewarded for accepting transactions with greater gas prices due to supply and demand.
Actually it is a common thing to happen on the Ethereum network when the transactions start to get crowded in the network, because in the past it was just like that, only because the price of Ethereum is still very cheap so Ethereum network users are not so stressed when making transactions, because the fees are still very cheap even though the spending figures are still the same as they are today.