Unlike the amd64 kernel, the arm64 kernel does not print system memory size during boot.
I'll look into this...
https://reviews.freebsd.org/D25625
A commit references this bug: Author: markj Date: Mon Jul 13 17:05:45 UTC 2020 New revision: 363162 URL: https://svnweb.freebsd.org/changeset/base/363162 Log: Print arm64 physmem info during boot. PR: 243682 Reviewed by: andrew, emaste MFC after: 1 week Event: July 2020 Bugathon Differential Revision: https://reviews.freebsd.org/D25625 Changes: head/sys/arm64/arm64/machdep.c
A commit references this bug: Author: markj Date: Mon Jul 20 13:30:42 UTC 2020 New revision: 363364 URL: https://svnweb.freebsd.org/changeset/base/363364 Log: MFC r363162: Print arm64 physmem info during boot. PR: 243682 Changes: _U stable/12/ stable/12/sys/arm64/arm64/machdep.c
Thanks for the report.