It looks like some problems with sockets are getting fixed quite soon
https://git.proxmox.com/?p=pve-kernel.git;a=commitdiff;h=c579c08545b636b97b7f2c14ede9e669e8d8595b
Could be that some programs try to chmod the socket after having created and disconnected from it. Which would explain that you could fix it by chmodding yourself.
But it can also be there are different problems involved.
https://git.proxmox.com/?p=pve-kernel.git;a=commitdiff;h=c579c08545b636b97b7f2c14ede9e669e8d8595b
Could be that some programs try to chmod the socket after having created and disconnected from it. Which would explain that you could fix it by chmodding yourself.
But it can also be there are different problems involved.