Refreshing the page on an activity form that has custom fields keeps the type but makes the custom fields disappear

Create an activity standalone (civicrm/activity&reset=1&action=add&context=standalone)
Choose an activity type that has custom fields.
Refresh the page using the browser refresh button.
The custom fields disappear, but the activity type field still has the selected type.

This does not happen when you create the activity from a contact directly (e.g. civicrm/contact/view/activity&action=add&reset=1&cid=274&selectedChild=activity&atype=103)

Since you are refreshing a page with "reset=1" in the url, the consistent behavior would be to also clear the activity type field.