Voice recording distorted on higher notes

There can be audio enhancements on playback & on recording devices.
In your case it’s the recording device enhancement that’s causing the problem …

Recording, Microphone, properties, advanced, uncheck “enable audio enhancements” …

https://www.elevenforum.com/t/enable-or-disable-audio-enhancements-in-windows-11.8426/

You could Google to see if your model of Dell computer comes with MaxxAudio (by waves)
If it does it’s on by default, and you should switch off it’s microphone enhancements.