A "repack" generally refers to a modified version of an APK. Regarding Google Play Services, you should exercise extreme caution: Download the APK from Uptodown - Google Play services
Google Play Services is a background service that powers core Android features:
continue to function correctly with improved synchronization across devices. Advanced Privacy Controls
Official GMS receives monthly security patches. A repack may lag behind, exposing your device to known exploits like "Dirty Pipe" or "Janus" vulnerabilities in older signature schemes.
If you are a power user with a rooted device, spare time to troubleshoot, and a backup plan—it’s worth experimenting. The performance gains on old flagships can feel like a new phone. But for the average user, the official Google Play Services, perhaps combined with simple battery optimizations (restrict background data, turn off Wi-Fi scanning), remains the safer path.