My Time Machine backups in Catalina are taking much longer than they used to. After I first upgraded Time Machine states my disk didn’t have enough free space, so I formatted the disk and started over. The initial back up took a couple of days for < 500 gigabytes but it finally completed. Now whenever it runs the incremental backups it hangs up on “Preparing Backup” for several hours and then takes a long time to back up small amounts (50 megabytes or so). My iMac also seems to be having random issues shutting down. All apps are closed when I shut down, and then it hangs for a few minutes and just reboots. Any ideas?