What can beep on a macbook?

Question

macbook

In April I bought a macbook pro, a couple of months ago a nasty squeak appeared (as if a mosquito was flying) from the left side. At the beginning, it reacted only to working with the touchpad or mouse, but then it just began to squeak like that. The squeak has no system, it can be silent all day, and in the evening start to squeak. I took it to the service center, they didn’t find anything there, they didn’t hear a squeak during testing. I recorded a video, I'll throw a link to YouTube, maybe someone has come across a similar one?

Link - https://youtu.be/ItkPWOyQoU0