I had the same issue and found that setting up to the homeassistant.local instead of the IP address worked. Not sure if that was a fluke though…
I do not think it is networking, they rather mess with webkit engine. More an more issues arise as they upgrade Safari. Many people on this forum reported issue when connecting from Safari using local IP:8123 connection (page not loading or requires several retries to reload to get content), using mDNS or external URL solves this. This happens only with Safari or apps using webkit. Other browsers (well, on Mac) do not have this problem.
Other issues are related to lading animated SVG, or the most recent: when loading HA from App all content is displayed properly, but when loading it as web page directly into Safari, some menu items are missing (Settings, Notifications, User Profile). The last one only on Mobile Safari. These issues started earlier, starting iOS26.
I’ve just done the same and that fixes it for me.
Set internal url on the app to
http://homeassistant.local:8123/
This works for me too, both on IOS 26.4 build 23E5223f and iPadOS 26.4 build 23E5218e
I have never been able to resolve internally with http://homeassistant.local:8123 i have always used http://192.168.x.x:8123 and now it stopped working internally through the app. Any ideas what can i do in that case