Hi winston9t4,
While it’s not always possible to to track down or quantify temperature regulation issues for any particular person on a specific mattress because there are so many variables involved (including your room temperature and humidity, your sheets and bedding and bedclothes, your mattress protector or any mattress pads you are using, and where you are in the “oven to iceberg” range) and some people can sleep warmer on mattresses that most people are generally fine with … there is more about tracking down a potential cause or causes for temperature regulation issues (at least to the degree possible for a specific mattress) in post #2 here and the posts it links to that may be helpful.
There is more information about the pros and cons of different types of mattress protectors and some good sources for each of them in post #89 here that should be helpful. The membrane type of protectors are less breathable than protectors that don’t have a waterproof membrane and along with your sheets and bedding can certainly have an effect on your sleeping temperature for some people regardless of the mattress you are using it on.
Phoenix