Indeed! If you're confirming that direct sunlight on your mobile device is causing the issue, then flying in the shade is likely the easiest solution. If there are no shady areas nearby, you could make your own shade.
Hi Riich,
Welcome to the forum from the outback of Australia. If you want more info on your construction progression, check out Richard Carpentier on you tube, very informative.
Regards
Gagey
Back in 2017, I started my drone flying with a SPARK and a iPad mini4.
I found the same problem you are experiencing and a sun hood helped and it is cumbersome.
I tried a 3 sided hood that didn't work well because the pesky sun light sneaks in...