@chapoi - I introduced some confusion by saying “custom field instructions” – I meant I had customized some default field instructions. I have no ‘user custom fields’.
@moin - I did have full name required enabled. Disabling this does change the field order back to match the tab order. I’m ambivalent about requiring the name, but either way the field order & tab order should match.
And I had missed the full page login screen announcement, but switching over to that confirms that the ordering issue is the same.
(Not huge stuff, but I appreciate the attention to the topic!)