Hello Kokpokii. To prevent your phone from sharing pictures with your PC, you must disable Phone Link or whatever sync feature you are using to sync your phone and the PC together. In Windows 11, go to Settings > Bluetooth & devices > Your Phone and then select your phone and then click Remove this device. This will stop any syncing, including picture sharing. If you are using OneDrive or any other cloud service to auto-sync pictures, open the OneDrive app, then go to Settings > Backup, and turn off Photos and Videos from this device.
This same situation often happens because someone turns on cross-device Sync without remembering doing it.
Let me know if you have questions or this helps.
Best regards,