It seems to only happen for certain algos and certain difficulties.
I'm seeing it right now on lyra2z. The pool is operating at diff 6.2 but he miner says it's 6.
This result in some low difficulty shares when the submitted share diff is between 6 and 6.2.
The rejected shares are mostly noise and don't affect performance.
I have not noticed the pool difficulty being lower than the miner but that would be a silent error
not easilly noticed. This would result in lost performance because the miner would discard shares
that would be accepted by the pool.
Changing stratum difficulty sometimes resolves the issue unless vardiff changes it back.
I had used sd=1 on the command line, stratum responded with 6 but the pool used 6.2.
I tried with sd=6.2 but stratum still responed with 6.
I tried sd=8 and it was accepted, both the stratum response and the pool said 8 as they should.
But vardiff stepped in and lowered the diff and they mismatched again.
Would like to investigate this issue more, if you could confirm above scenario was done on lyra2z? what miner did you use?
If possible reach me out in discord for more details. (e.g. wallet URL and time frame, so I can search in logs).
Sorry for coming with delay, not checking forum as frequently as other zergpool support channels