Last Name field w/ User Integration - multiple words and letter casing

[vonscriptor]

Two problems here:

1. If a last name value like: "Sanchez Maselli" is saved "Sanchez" is removed.
2. A last name value like : "Van Holtz" is saved as "van Holtz" losing its title case.

Is there a name parser that Freeform uses that is trying to normalize the names?

Steps to reproduce

1. Create a form with a text field that uses a User integration to a user's last name field.
2. Enter in a value like "Sanchez Maselli". "Sanchez" will be lost.
3. Enter in a value like "Van Holtz". The uppercase "V" in "Van Holtz" will be lowercased.

Expected behavior
The full last name should be saved.
The letter casing should be kept.

Craft & Plugin Info (please complete the following information):

• Craft Version: Pro 4.8.6
• Freeform Version: 5.1.8
• Freeform Edition: Pro
• Fresh Install or Upgrade: Fresh

Additional context
I created a similar issue thinking this was a Craft issue, but it's not after additional testing and feedback from Brandon.
Reference: craftcms/cms#14723