Messages stuck with a landscape (sideways) keyboard with Messages in portrait mode, iPhone 12 mini

On an up-to-date iPhone, 12 mini in this case, without screen locking going on, Messages becomes struck with a landscape (sideways) keyboard with Messages in portrait mode. The Messages input field can show only one or two characters while in this mode. This arrangement, being almost useless, is most likely not intended by the application. Other application keyboards are not in this mode. A device force restart restores Messages to a normal operation.

This problem has been reported by many in this Community, even going back by years. There is never any explanation as to how or why it happens or how to reset the Messages application other than by suggestions to shut down and then restart the device. Am I to assume this is indeed an unintentional mode with no simple settings change to revert the keyboard?