This has affected 2 out of 10 iterative ndrpdr runs in rls2410 testing. Not clear if this is specific to 9000B tests. The 2n-zn2 is the first testbed where this happened, will update if more testbeds are susceptible.
This is a dpdk bug or infra failure. CSIT-1960 is another example of an issue on 2n-zn2 that stops forwarding in one direction, so this may be the same issue with different dut.
Currently we do not run dpdk ndrpdr tests in trending, 64B mrr tests do not seem to be affected.
Link to log.html: [0].

[0] https://s3-logs.fd.io/vex-yul-rot-jenkins-1/csit-dpdk-perf-report-iterative-2410-2n-zn2/4/log.html.gz#s1-s1-s1-s1-t6-k2-k5-k14