Last author is saved as "Unknown User" when trying to vote as a Guest user

[ane-gabriela]

Preconditions: Have some ideas already created.

1. Steps to reproduce:
2. Access the Ideas home page as a Guest
3. From the Ideas livetable click on Yes / No for an idea
4. Refresh the page

Expected results: The guest users aren't allowed to vote.

Actual results: The guest user is not allowed to vote but after the refresh of the page the Last author is changed to "Unknown User".

NOTE: This also affects the History tab and the information seen in the Ideas Macro

Environment: XWiki 11.3.5 with MySQL 5.7 and Edge 18, Ideas Application (Pro) 1.11.12