2021 STI here, Cobb 91 map and low load does the same. Its the ecu doing its job honestly. Had a tuned WRX and I could feel a big difference from an aggresive tune to a full good etune, but tamer. If you see the numbers going back to 0 quickly, its just ghost knock.I know this is an old thread, but please tell me you found a solution to your problem.
I have a 2017 with the same issue, except when on a 93 Cobb map I get DAM drops and FKL. On 91 map I don’t.