Cannot record audio as mono

[lrdgreen89]

I'm an audio engineer using Zoom-meeting recorded audio files regularly. My client sends me their files, I edit them. They used to always be mono files. Then sometime around October of 2024, the files started being stereo. It would help me if they were mono. But I can't find an option in settings to record mono vs. stereo. If I found a way to make them mono like previously, I'd inform my client.
Any help?