It's a known problem that only occurs when mining on nanopool, we're looking into it. Mining on other pools is unaffected.
Which version? If 0.21.2, could you upload the log file?
20210709 19:49:34.327[784846.552] <-IN-66-0 {"id":216934401,"result":false,"error":[1,"Share above target."]}
20210709 19:49:34.437[784846.656] [FAIL] 1158/1163 - Share above target., 255ms ... GPU #1
20210709 19:49:34.437[784846.660] autolykos.eu-north.nicehash.com:3390 asks job 00000000db3e4a50 for block 528488
20210709 19:49:40.614[784852.835] -OUT-> {"id":218581763,"method":"mining.submit","params":["*************.****************","00000000db3e4a50","9a584ea21c","00000000","108a8e9a584ea21c"],"worker":"Farm2"}
20210709 19:49:40.802[784853.032] <-IN-66-0 {"id":218581763,"result":false,"error":[1,"Share above target."]}
20210709 19:49:40.864[784853.093] [FAIL] 1158/1164 - Share above target., 257ms ... GPU #3
20210709 19:49:40.864[784853.096] autolykos.eu-north.nicehash.com:3390 asks job 00000000db3e4a50 for block 528488
20210709 19:49:41.722[784853.954] <-IN-229-0 {"id":null,"method":"mining.notify","params":["00000000db3e4a51",528488,"b7de423bd2296543770a31e637a70b4782fc01d9dd52211e3a06ff4e53e7f58d","","",2,"41157205394722105456231126733432809649589828953424482219666653390575","",false]}
20210709 19:49:41.816[784854.038] GOT NEW WORK job_id=00000000db3e4a51, old: job_id=00000000db3e4a50
20210709 19:49:41.909[784854.129] WARN: New iteration find nonces for device [ID=1, GPU #1]: job_id=00000000db3e4a51
20210709 19:49:41.909[784854.129] WARN: New iteration find nonces for device [ID=4, GPU #4]: job_id=00000000db3e4a51
20210709 19:49:41.909[784854.129] WARN: New iteration find nonces for device [ID=2, GPU #2]: job_id=00000000db3e4a51
20210709 19:49:41.909[784854.129] WARN: New iteration find nonces for device [ID=3, GPU #3]: job_id=00000000db3e4a51
20210709 19:49:41.940[784854.173] WARN: New iteration find nonces for device [ID=0, GPU #0]: job_id=00000000db3e4a51
20210709 19:49:53.594[784865.814] -OUT-> {"id":221904387,"method":"mining.submit","params":["*************.****************","00000000db3e4a51","99beb24d00","00000000","108a8e99beb24d00"],"worker":"Farm2"}
20210709 19:49:53.734[784865.965] <-IN-66-0 {"id":221904387,"result":false,"error":[1,"Share above target."]}
20210709 19:49:53.828[784866.057] [FAIL] 1158/1165 - Share above target., 243ms ... GPU #3
20210709 19:49:53.828[784866.061] autolykos.eu-north.nicehash.com:3390 asks job 00000000db3e4a51 for block 528488
20210709 19:49:55.512[784867.734] -OUT-> {"id":222395649,"method":"mining.submit","params":["*************.*************","00000000db3e4a51","335e6ed01c","00000000","108a8e335e6ed01c"],"worker":"Farm2"}
20210709 19:49:55.653[784867.886] <-IN-66-0 {"id":222395649,"result":false,"error":[1,"Share above target."]}
20210709 19:49:55.762[784867.995] [FAIL] 1158/1166 - Share above target., 261ms ... GPU #1
20210709 19:49:55.778[784867.999] autolykos.eu-north.nicehash.com:3390 asks job 00000000db3e4a51 for block 528488