Please upload the file to Dropbox or other file sharing site and I'll take a look.
Here is one of the photos that had the problem, I transcoded it to DNG format so you can view the lens correction changes in the software. This problem mainly occurs with Lr on iOS, which can't manually select a profile, so I'm guessing it may have applied the L-mount file incorrectly.
I hope you can find the problem as soon as possible, this problem is too serious for users who often use mobile outdoors, thanks a lot!
At the below post with the same issue the user found that turning off in-camera shading compensation reduces the excessive vignetting correction.
Looking at your DNG file in LrC it's showing 'Built-in Lens Profile' applied. That profile includes distortion, chromatic aberration, and vignetting corrction. If I uncheck 'Enable Profile Corrections' the vignetting correction is insufficient with darkened corners. A v2 lens profile is being applied in LrC. If I change it to the v1 profile (i.e. no version number) the vignetting correction appears correct. Unfortunately, LR Mobile on iOS does not allow manually selecting a different lens profile. For the pictures already in LR Mobile you can use LR Desktop or LR Classic to process them using the v1 lens profile. Going forward try turning off the in-camera shading compensation setting and see if that fixes the issue.
Hi, I did some testing over the past few days and used the method in your recommended post to turn off in-camera correction, and the bright angle problem that appeared before with the iOS version of the Lr was solved, but this would again make the desktop version of the Lr's auto-correction appear with bright corners, which would need to be manually adjusted to the L-mount version to work properly. In short, I guess because the Sony body exists dark angle correction function and the Sigma body does not, so the E mount version of the profile dark angle correction is not as large as the L mount version. But the iOS version of Lr may have had a recognition problem with the recent update, which incorrectly applied the L-mount profile causing the bright angle problem. I hope you can give feedback to the development department of Lr for iOS and fix it in a future update - after all, this problem has never happened before. Finally, thank you very much!
"But the iOS version of Lr may have had a recognition problem with the recent update, which incorrectly applied the L-mount profile causing the bright angle problem."
Try changing the lens profile in LR Desktop app. It should then sync to LR Mobile on iOS. Please let me know. It works with LR Mobile on Android.