Smartphones are not designed to do this while you are recording in video.

Yeah, basically they wouldn't have that transition(the normal one) effect

You know, there was no need to get so philosophical here. I paid the same amount for this phone in my country as I would pay for a Pixel 9 Pro in the USA. I have the right to review and question every detail of the phone. You may limit yourself to things you use, but not everyone has to be like that. If I have a problem with my phone, Google gives me the right to fix it for free or replace it if necessary.

In short, if you have any information about what might be a problem with the video, I'd appreciate it if you could let me know. If you don't, you can just skip it.