Raise to Listen is toggled off but that recording symbol is still present on messages

That does not mean the iPhone is listening. That is the button to press if you want to send a Voice Message. If you go to  Setting > General > Keyboard > Enable Dictation, you have the option to see the microphone button there that is used for Voice Dictation of your Messages. The option you see there will be the last one used for that Contact.

If you have the Microphone button for Voice Dictation and want to send a Voice Message, then you would tap the + button next to the message and choose Audio. You will see either the Microphone button or the Voice Message button that you see in the Screen Shot. With Dictation disabled, you will only see the Voice Message button.