Nothing happened, Ethereum only has a scalabillity problems. Many developers would like to create dapps on Ethereum but they are pushed to pay higher fees for slower transactions, so they are migrating to another smart contract platforms.
Yeah, Ethereum is currently a bit of a victim of its own success. Because for a long time for almost every project Ethereum was the number one choice. That caused more and more traffic on the blockchain and longer transaction times. It will be interesting to see how Ethereum (and also other projects) solve the scalability issue. For Ethereum to evolve and also gain wider adoption/usage the current tps aren't enough.