Change "no profile picture" picture

Is your feature request related to a problem? Please describe.
The image of the "U" is not very user-friendly. One does not know for what the U stands and why it isn't the first letter of their entered name and such.

Describe the solution you'd like
Change the U to be the first letter of the first name that the user entered for their account if they have not uploaded a profile picture yet.

Describe alternatives you've considered
Use a consistent, more user-friendly image

Additional context
Here is one example of the alternative described: