[CentOS] kernel: net_ratelimit: 18 callbacks suppressed

CentOS 7.9 system. My 2 servers at home have been spewing this error message every few minutes to /var/log/messages. But there's no preceding message to tell me what's being suppressed. From googling for this, I understand that the failure to log the real message is a bug in the v3 series kernels and v4 fixes that.

2 servers at the office and another on a VPS with 7.9 do NOT issue this message. So I'm guessing something on my home LAN is causing it. Running tcpdump, I don't see any correlation between LAN traffic and ratelimit messages, though.

Any suggestions on how to diagnose this?