I use Teamredminer for my AMD system and I'm testing T-Rex miner for this RTX 3080. The reason I'm not using Phoenix miner anymore is because it inflates hashrates by about 3%.
https://github.com/Kerney666/trm-ethash-miner-testerI have seen the same results when I'm mining. You can never hold your average hashrate poolside, it's off by about 3-5% in the long run with Phoenix. This means that 98Mh/s in teamredminer is actually more efficient than 100Mh/s in Phoenix miner.
T-Rex seems to show true hashrates so far but I have to do more testing.