Hello Lyds_squid,
Thanks for the post in Apple Support Communities. If I understand your post correctly, you may be having a keyboard issue on your iPhone.
It sounds like you may be typing and find that the keyboard stays up and active even after you're done typing; is this correct? Does this happen when you're typing in a specific app, or every app?
When you mention a "Banish Keyboard" icon and a mic and globe, can you provide a little more detail about what you mean?
Does the same behavior occur if you rotate your iPhone and try typing? You can learn more about rotating your display here: If the screen doesn't rotate on your iPhone, iPad, or iPod touch.
Does it help if you Restart your iPhone, iPad, or iPod touch?
You mentioned iOS 12; under Settings > General > About, are you using iOS 12.1.2? If not, here's How to back up your iPhone, iPad, and iPod touch and Update your iPhone, iPad, or iPod touch. Then, test it out to see if updating has cleared things up.
I hope this helps!
Take care.