Louis Rossmann has a video series of his rants about commercial real estate and the refusal of landlords to rent spaces to him which have been vacant for multiple years.
One of his videos speculates that real estate is being used to store money and the building owners don't want to rent out anything:
https://www.youtube.com/watch?v=Yavgfk0IjdM
Another video speculates that the owners of some buildings have made claims to banks and investors that their buildings are worth more than these buildings are actually worth. In this situation, if the buildings' owners lowered rents they would be admitting that the building is not worth as much as they claim. This could trigger contractual obligations they have with their mortgages and investors: