Yes there are bicycle holders similar to the ones in this image https://www.fr.de/bilder/2022/05/24/91569582/28956265-die-orangefarbenen-mietraeder-von-meinrad-sind-aufgefallen-in-der-stadt-2ObFGch86bfe.jpg

As far as I know the city plans to revive its bike renting system at some point in the future so it is likely these bike holders will not be removed.

It is unclear whether these are in use by the bike rental service of nextBike atm. 