Hi, thanks for reaching out! Please allow me to assist you.
I feel this is normal behavior. There are temporary files that cannot be cleaned up until you have restarted the computer, because these files could be locked by an application and therefore can only be marked to be deleted later.
When you shut down your computer and assuming Fast Startup feature is enabled, your computer would be placed into a hibernation state instead of a full shutdown. This may not unlock certain temporary files for clean up, especially if an application continues to lock it. Hence, a restart works.
I hope these explainations help. Please let me know if I can help you further!