Time Machine Initial Backup Larger Than Hard Drive Size

I am in the middle of an initial backup of a 2020 MacBook Pro. The hard drive is 1TB. There are 250GB free, so 750GB used, approximately. The backup is being done over WiFi. We are currently on Day 11. Time Machine status says it has completed 1.24TB so far, and it is still going. The computer is still running Mac OS 14. Trying to complete a backup before doing the updates to get it up to date. I am backing up to a new Synology DS224+ with 2 new 12 TB hard drives. The router is an ASUS, new in the last 2 years, so speeds should be decent locally. I have been using the computer, but I am not making huge changes to it. Has anyone seen this, or can help me understand what is going on? Is this a normal amount of time for an initial backup? Any help would be appreciated.