It seems that if you speed up the cooling fan, it might be better. Did anyone used a manual fan controller for 2018?
When you have to use a third-party solution of any kind to resolve an issue that shouldn't be happening in the first place, yeah, that's a pretty clear indicator that something is terribly wrong. I'm not saying that this issue can't be alleviated to various degrees (pun very much intended) with the adjustment of the fan curves, but even so there's that underlying question of "How the hell could Apple ship something like this in this particular state of functionality knowing that professionals need Final Cut Pro and Premiere Pro and some other CPU-intensive applications and programs to perform at their best and they should considering the crazy premium pricing they're paying for said performance?"
I mean it's really that simple: if the product isn't doing what it should be doing and providing the level of performance it's supposed to provide - and some people will say that when it throttles it's doing exactly what it's designed to do, which is true again to some degrees but also a crappy line of reasoning to use as a defense of the lame throttling performance - then by all means, send it back to Apple or return it and teach them this kind of situation is simply not acceptable for the given level of pricing on these products.
If people just continue to shrug it off and let Apple continue these kinds of practices, well, that's on the people gladly forking over excessive amounts of money for the "privilege" of using Apple products I suppose.