I built OpenWRT 19.07.3 from sources for TP-Link TL-WR841N V13 last week before 22.08.2020 and snmpd worked.
But when I've built it today 24.08.2020 snmpd got broken.
root@p78:~# service snmpd restart
root@p78:~# logread -f
Mon Aug 24 17:53:14 2020 daemon.info procd: Instance snmpd::instance1 s in a crash loop 6 crashes, 0 seconds since last crash