When a user inserts a pin on the map, a message bubble is inserted to the chat, but that bubble looks almost like any other text message, except for the tiny pin icon next to the timestamp.
So it may be challenging for recipients to comprehend. As the text may be something terse like “meeting point” or the name of a shop, the reader would ask why is my contact sending me a text message saying only “meeting point”?
Suggestion is to let such messages have somewhat different styling, maybe similar to forwarded messages which have a special heading in a different typeface.
And also have a button that would open the map and highlight that location.