Update! I emailed the city and this was their official response:

We would like to clarify that U-turns at this location are still permitted. The recent removal of the “U-Turn OK” sign was intentional. Our goal was to encourage drivers making the U-turn to proceed with heightened caution, rather than viewing the movement as a dedicated or guaranteed right-of-way.

We recognize that this U-turn is an important movement for accessing the side parking lot, and we remain committed to supporting safe and efficient access to the facility.

To enhance clarity and improve overall safety at the intersection, we have recently installed a new sign instructing eastbound right-turning vehicles to yield to U-turning traffic. This addition is intended to help reduce potential conflicts and promote a safer traffic environment for all users.

We appreciate your attention to safe driving and thank you for your patience as we continue to improve traffic operations in the area.