I have the previous version (gen 6) and I can confirm the heat problems. You can not watch a 4k movie and charge it at the same time. Soon after you plug in the charging cable the upper left corner of the computer will be so hot that you (almost) can burn yourself. When that happen the computer will slow down to the point where it is not really usable.
At this point you can turn the computer upside down to allow the back side of the computer to cool down (get some air). After a few minutes it has cooled down sufficient to that you can continue using the computer and charge it at the same time, but shortly after you will have to repeat this.
If think the backside of metal case get so hot that not enough hot air cannot escape. If you can place the computer in any position that allows air to flow over the back side of the case everything works, but placed on a table or similar you have severe thermal issues if you charge it at the same time at the same time you do anything mildly CPU intensive.
At this point you can turn the computer upside down to allow the back side of the computer to cool down (get some air). After a few minutes it has cooled down sufficient to that you can continue using the computer and charge it at the same time, but shortly after you will have to repeat this.
If think the backside of metal case get so hot that not enough hot air cannot escape. If you can place the computer in any position that allows air to flow over the back side of the case everything works, but placed on a table or similar you have severe thermal issues if you charge it at the same time at the same time you do anything mildly CPU intensive.