Still seeing Failed assertion: "p[i] == 0" on armv7 buildworld

I'm still getting buildworld stoppages on armv7, with reports of 

<jemalloc>: /usr/src/contrib/jemalloc/include/jemalloc/internal/ehooks.h:170: Failed assertion: "p[i] == 0"

seemingly at random, but only while building libraries. If buildworld is 
restarted, it picks up where it left off using meta mode and gets somewhat 
farther along before stopping again.  Eventually it finishes. At least
one buildworld ran to completion without stopping, but that's the exception.

The machine is a Pi2 v1.1, USB mechanical hard disk, headless with
serial console and ssh access.

Uname -a reports
FreeBSD pelorus.zefox.org 16.0-CURRENT FreeBSD 16.0-CURRENT #5 main-n281033-033587a985a4: Fri Oct 10 02:10:37 PDT 2025     [email protected]:/usr/obj/usr/src/arm.armv7/sys/GENERIC arm

Uname -KU reports
1600001 1600001

Any suggestions? The serial console emits no recognizable complaints/warnings.
At this point it's unclear if the trouble is upstream, local or hardware.
Apart from this one failure mode the machine, one of three exhibiting the same
behavior, seems stable.

Thanks for reading,

bob prohaska