In the end I solved this (hackishly) by editing
.local/lib/python3.10/site-packages/tutor/templates/apps/openedx/config/partials/auth.yml
and removing some sort of conditional it had
{%- if RUN_MYSQL %}
charset: "utf8mb3"
{%- endif %}
and replacing that with just
charset: "utf8mb4"
(This being under the DATABASES → default → OPTIONS heading)
This doesn’t really make sense still though, as to why it works with no change my beta Palm platform and it doesn’t work on the production Palm patform. My .local/share/tutor/config.yml
has RUN_MYSQL: false
in both cases…