After looking into it further, it seems to be an issue with Macs and Microsoft teams
It is video-conferencing in general. The same thing happens with both Zoom and Webex meetings on my 2017 iMac and my 13-inch MacBook Pro. Friends with Win computer report hearing their fans as well.
Video conferencing is as demanding on the CPU and GPU as any other videos app. I have a temp monitor on my iMac; increased temps indicate increased workloads. A one-hour Zoom or Webex meeting will run temps recorded to the same level as graphics-intense games and sims.
Fans are thermostatically controlled. if the temps get too high, the computer will clock back to reduce heat and, that failing, will shut down before you hear components frying.
I am now having to use an old back up laptop, since it has no issues with Microsoft teams.
What models are your two notebooks? Is the "old" one Win or Mac? Older notebooks, especially older Win notebooks, commonly have bigger and/or more fans. Mac notebooks with 15- or 16-inch screens have two fans; 13-inch MBPs have but one. Smaller is hotter.
Make sure you are not using the MBP in your lap or on a pillow. Apple does not call these computers "laptops." There are important air vents in the hinge area and, depending on model, around the edges of the base place and the openings between keys on the keyboard that must remain unobstructed.
Keep your Mac notebook within acceptable operating temperatures - Apple Support
Assuming:
- you are not positioning the computer in a manner that blocks the vents and,
- you have not burdened it with unneeded anti-virus or so-called "cleaning" apps that will increase the workload,
then you can consider a fan control program. You can manually set up the fans speed to a level that is not disrupting to you or other attendees. I believe that, depending model (which we don't know), you can set the fans to the 2700-3000RPM range and not have them be intrusive. Depending on model (again), the max fan speed is 6000RPM; half speed should not be an issue.