[test-triage] kmac_masked/kmac_mubi regression failures

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### Hierarchy of regression failure

Block level

### Failure Description

Seed-dependent failures of kmac_unmasked/kmac_mubi:

UVM_FATAL @ 1014685123 ps: (kmac_scoreboard.sv:1638) [uvm_test_top.env.scoreboard] Check failed unmasked_digest[i] == dpi_digest[i] (223 [0xdf] vs 35 [0x23]) Mismatch between unmasked_digest[0] and dpi_digest[0]
UVM_INFO @ 1014685123 ps: (uvm_report_catcher.svh:705) [UVM/REPORT/CATCHER]
--- UVM Report catcher Summary --

### Steps to Reproduce

- GitHub Revision: 4674f625b3
- dvsim invocation command to reproduce the failure, inclusive of build and run seeds:
./util/dvsim/dvsim.py hw/ip/kmac/dv/kmac_masked_sim_cfg.hjson -i kmac_mubi --build-seed 27137705585251537962012108482438895412147493342955425380690984800523869492310 --fixed-seed 35231741526337024530576263461083927902011999408154303379202531862439254637186 --waves fsdb
- Kokoro build number if applicable

### Tests with similar or related failures

- [ ] kmac_mubi.35231741526337024530576263461083927902011999408154303379202531862439254637186
- [ ] kmac_mubi.95447557476775588777259967905051197010575041645731491136911029779147692977046

Start with hw/ip/kmac/dv/kmac_masked_sim_cfg.hjson and the failure at kmac_scoreboard.sv:1638. Run the provided dvsim command with the listed revision and seeds, then compare the failing kmac_mubi behavior with the related seed failures. Done means identifying and correcting the regression cause and confirming the affected simulations pass.

Written by the indexing model from the issue text.