Along with the transition of Ethereum to POS, miners lose their profitable business. Accordingly, they resist this and the only solution for them in this situation will be a fork that will allow them to continue to receive profit from mining. But it can be assumed that it will not be as profitable as ETH mining.
Well i can totally understand that those big mining companies that are mainly in China are not very happy that Ethereum will switch to PoS soon as they have invested Millions of Dollars into their mining farms and most of them are using ASIC's to mine Ethereum which means they can not just switch to mining Bitcoin as it is using a different algorithm.
That being said, it is known for some years now that ETH will become proof of stake so those companies had a few years to prepare for that moment that will come now in a few days.
I doubt that their ETHW fork will be really profitable. It is just a desperate move in my opinion, but we will see.