Zwift Apple M1 support - now 4K and high details

Hi folks,
ZWIFT on iMac Retina 5K, 27", 2020, 3,1 GHz 6 Core Intel i5, 8 MG DDR4 runs since upgrading to Ventura 13.5 in 1440p AND UHD 2160p mode. Before highest resolution was 1080p. Even in 1440 and 2160p with fluently graphics! Any idea why?