I have noticed that when importing a locked clip via the Varia app into Photos (on iPhone), during playback it seems to have something like a 4:3 aspect ratio rather than 16:9, with the sides cropped off. If the clip is then exported from Photos (Mac) after syncing via iCloud, it then results in an uncropped 4:3 video, with everything squashed horizontally. If I export the original unmodified clip, it plays back fine, although if opened in QuickTime, it's cropped again. The only workaround I have to ensure the correct aspect ratio with no cropping is to convert into a different format using HandBrake.
The Varia RCT715 has never done this.
Varia Vue has latest firmware (5.40)
iPhoneOS 18.4.1, macOS 15.4.1
Looking at the EXIF data, the image stabilised size (2688x2160) may be contributing to this. Possibly some discrepancy with pixel aspect ratio, and sample vs display AR.
Image below shows what it looks like played back on the phone.
This shows playback on Mac after exporting from Photos