Hi
My test on the mobile client successfully reproduced your problem, which should be due to the design of Teams meeting recording.
Please try to join the meeting on the desktop client and check if the recording file is cropped.
To fix the problem more quickly, I have found a feedback in Teams UserVoice and you could vote for it. Many features of our current products are designed and upgraded based on customers' feedback. With requirements like this increase, the problem may well be released in the future. Thanks for your understanding and support.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.