the ETC community associated with Phoenix Miner has decided to carry out a HARD FORK during the Block 10.500.839 (originally announced on June 10, close to June 02 due to mining, currently the increasing difficulty (as well as its course) does not allow to specify more than that the exact date, only the block chooses is authentic)

This Fork intervenes mainly to get closer and take charge of the MAJ of Fork Istanbul on its big brother ETH.
6 EIPs were selected, roughly the Blake2 compression function to precompile the information, the reduction in GAS cost for transactions, the addition of the ChainID opcode

The underlying objective is still the POW on ETC (logical since the FORK is supported by one of the best miner etash on the market) unlike ETH which is moving more and more quickly towards the POS, its last parallel blockchain test being successes for the moment.
To summarize (sorry if I was draft in the explanations)
Interoperability: Establishment and maintenance of interoperable behavior between existing Ethereum customers Immutability: The addition of opcode is only a supplement to the already existing contract, it will not change their behavior (for current contracts) Le Hard Fork is required, changes are not backward compatible. Therefore we can ask the question, will there be a big pool that will decide to stay on the current ETC during the Fork?

There is no more info on the mining itself, if phoenix miner would be updated for this fork, I would not fail to keep you informed (as for claymore, its direct competitor)
Regarding Ethereum customers / nodes, there will be many mandatory majs. The 4 customers following the Fork test to make it compatible with the general public on D-Day: Core-Geth / Hyperledger Besu / Multi-Geth / OpenEthereum

the ETC logo has been reworked on the Fork announcement page, we can clearly see the Phoenix of the software associated with the graphic charter of ETC.