When mining Ethereum are there anything like lucky shares? I heard one can make more once in a while depending on luck though, there was a news when DeFi hype was ongoing in 2020 too that miners are making extra, can someone explain more about this?
I think you are referring to a lucky "block" and not a lucky share. When you are mining you send shares to the pool, when they are over a certain difficulty they are counted and its whats used to estimate your hashrate and pay you a portion based on your work. If you are pool mining then it doesn't matter if you find the lucky share which is a block because you are still paid the same.
So every block has a miner reward plus transaction fees. With ETH especially during the DeFI craze or when ETH hit a new ATH, the transaction fees were very high. Something like $5 to send a single ETH transaction and for DeFI were more like $50.
So its possible that you can get very lucky, find a block where the reward is 4x the regular reward.