Context: in May 2023, Tiki trunk/master changed requirements from PHP 7.4 to 8.1. So if you have some Tiki instances running trunk/master with Virtualmin Tiki Manager, they will not upgrade automatically.
cd /opt/tiki-manager/app
php tiki-manager instance:edit
To do: explore if php tiki-manager instance:detect
could be improved to handle this
GUI: Services -> Tiki Manager -> Instance Update -> Update
As of 2023-05-20, you may get an error "Updating Tiki Packages... may take a while ERROR Failed to update Tiki Packages. Check /opt/tiki-manager/app/logs/trim.output for more details" This will be solved shortly.