Part of it is about quality. These new formats now support 10+ bit color depth (which is critical for modern displays and for HDR) and full 4:4:4 chroma subsam

Part of it is about quality. These new formats now support 10+ bit color depth (which is critical for modern displays and for HDR) and full 4:4:4 chroma subsampling (to preserve pixel-level as needed). Many apps/services are currently evaluating or already migrating to AVIF or HEIC because these formats unlock those improvements in image quality, even without a major reduction in file size.