A 640 kbps repack offers a significant reduction in file size compared to a FLAC file (which can be 2000+ kbps) while providing a safety net of quality that satisfies the human ear. The "Upsampling" Trap
If you are listening via Bluetooth earbuds from your phone, a 192 kbps Opus file will sound identical. Furthermore, downloading a "640 kbps repack" from a shady public site is a great way to get malware, not superior audio.
If you see a "640 kbps Repack," check the source. Unless it’s a specific rip from a Blu-ray audio stream (AC3/DTS), it’s likely just a bloated file taking up extra space on your drive for no reason.