Something is eating up my MacBook Pro hard drive space

If you just restored the drive, don't worry about it.

Time Machine backs up the raw data files that are important, but the OS also uses a LOT of temporary and cache files for performance. These files are not backed up because they are, by definition, transient, but when you restore your system they need to be rebuilt, and the chances are that's what's happening here.

For example, the system has a built-in indexing system called Spotlight which you can use to search for files by type, content, name, date, etc. This database will be blank when your system is restored, and the OS will take some time to rebuild the index.

Similarly, when you restore your photos, Photos.app will scan the photos identifying people, places, pets, etc. so you can find them later. This index will also need to be rebuilt after a restore, and that takes more disk space, too.

So the chances are this is just normal housekeeping getting your system back to peak performance. It will settle down soon.

If it keeps going for an extended period of time (e.g. days), or the available disk space gets really small, then it may be something to worry about, but at this point there doesn't seem to be anything amiss.