Stick-up Cam Occasional Low Resolution Video

I have recently installed a stick-up cam plug-in. I've set it up to capture snapshots every 30s. The snapshots are always 640x360 which I understand to be correct (unfortunately). Video is 1920x1080 as expected and usually looks good too. However I am finding occasionally that video is low quality on par with the snapshot quality even though the downloaded video files are still 1920x1080. The video is low quality both as seen in the Ring app and when downloaded. I've seen this problem in motion, person detected, and live video. I've tried rebooting the camera which made no difference. Here are some comparison crops from a snapshot picture, snapshot video, and both a bad and good example of a motion video, all downloaded from the Ring android app. You can see that the quality of the bad example of the motion video looks essentially the same as the snapshots even though the downloaded video is 1920x1080 whereas the good motion video is properly 1920x1080.  I don't think this problem is caused by any network issues with my setup. I have full fibre to my home with 100Mbps both down and up. The camera is very near to the wifi router and reports green RSSI-43. The stick-up cam has been setup from new as outdoors wired. I also have a floodlight cam wired pro which is set up similarly to take snapshots every 30s (which are also 640x360 too unfortunately) and I haven't observed any video quality issues with it, they are always excellent. My best guess is that the stick-up cam firmware has a bug meaning it sometimes fails to properly switch from the 640x360 resolution used while capturing snapshots to the 1920x1080 resolution when it starts a video or live view. However it's also in the back of my mind that the camera may be faulty. I've noticed that every 1-2s the picture goes a bit blurry almost like it's re-focussing, my floodlight cam wired pro doesn't do this either. Anyone know whether this is a known bug with the stick-up cam or whether my camera may be faulty? Thanks for your help, Andrew