I was bothered about the same thing but it looks like in the Gmail app you can configure the left/right swipes separately to "Archive", "Delete", "Mark as read/

I was bothered about the same thing but it looks like in the Gmail app you can configure the left/right swipes separately to "Archive", "Delete", "Mark as read/unread", "Move to", "Snooze" and "None". The default seems to be both set to "Archive".