As much as I like Joplin, usability on mobile has never been its strength. One simple suggestion for improvement: Introducing a button on the right hand side of the note title field which can be used to clear its contents by a single tap. A small circle with an "x" in it would do the job.
It's a good thing that Joplin can autofill note titles with the first line in the note's body. But when you create a new note by sharing a picture into Joplin you get a long unique identifier as the note title which is meaningless. In this context (and many others) a button to clear an input field would be handy, which is a standard feature for mobile platforms such as Android or iOS.