Been having a play about with ef core and been having an issue with the include statement. For this code I get 2 companies which is what i expected.
I test your code, this problem exist in my test. in this post LINK Proposed that use data projection. for your problem Something like the following, is work.
[HttpGet]
public dynamic Get()
{
var dbContext = new ApplicationContext();
var result = dbContext.Companies
.Select(e => new { e.CompanyName, e.Id, e.Employees, e.Admins })
.ToList();
return result;
}