I tried a bunch of third-party iOS browsers including Firefox, Firefox Focus, Chrome and Brave and I don't face this issue anywhere else.
I believe Apple forces all third-party browsers to use WebKit underneath, so I feel this must be some recent change in Orion that has caused it to have a signature that triggers Google's detection.
I did try checking user agents of the browsers to see if there is anything out of the ordinary and noticed that Orion does not report the correct iOS version (I am on 17.7):
Orion: Mozilla/5.0 (iPhone; CPU iPhone OS 17_6_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.6.1 Mobile/15E148 Safari/604.1
Safari: Mozilla/5.0 (iPhone; CPU iPhone OS 17_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.7 Mobile/15E148 Safari/604.1
Brave: Mozilla/5.0 (iPhone; CPU iPhone OS 17_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Brave/1 Mobile/15E148 Safari/604.1
Chrome: Mozilla/5.0 (iPhone; CPU iPhone OS 17_7_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) CriOS/147.0.7727.47 Mobile/15E148 Safari/604.1
Firefox Focus: Mozilla/5.0 (iPhone; CPU iPhone OS 17_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/148 Mobile/15E148 Version/18.6
Firefox: Mozilla/5.0 (iPhone; CPU iPhone OS 18_7 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) FxiOS/149.2 Mobile/15E148 Safari/604.1
I tried changing Orion's user agent to Safari's one and while anectodal, I feel I am hitting captchas less frequently.