laptop restarts

I teach on Zoom 4 days/week.  On those days if I teach for 2 hours in the morning , and then  later in the afternoon I go to teach again on zoom, I find may laptop has restarted.  this is ONLY the case when I've been using Zoom.  on days I don't use zoom I can use the laptop in the morning and then later use it again and it hasn't restarted.  In spent a long time with Apple support and they could not find any reason it would do that unless it was some sort of Zoom setting.  I can't find any setting that would explain that.