According to the current official manufacturer information, the 2025 Samsung OLED TVs support G-Sync, but G-Sync is not explicitly listed for the QE48S90DAE (S90D, 2024) model according to the available product data. G-Sync is not mentioned as a feature in your product specifications and the official announcements refer to the 2025 models.

I'm not entirely sure if your model supports G-Sync. The information I have does not clearly cover this. For a definitive answer, I recommend checking the manual or the official Samsung website.