I never worked with Unity myself but I worked with people using Unity as their game engine, they all had problems with stuttering caused by the GC at some point.
You can try to search Unity forums about this subject, you'll find hundreds or thousands of topics.
What really bothers me with GC is that it solves a pain I never felt, and creates a lot of problems that are usually more difficult to solve.
This is a typical case of the cure being (much) worse than the illness.
What is Unity’s STW time? Is it optimized for latency? If not, you’re using the wrong collector. The pain point it solves is time spent debugging memory issues and generally a slower pace of development, but of course if you’re using a collector optimized for throughout, you’ll have a bad time. Further, a low-latency GC will pay off more for people who haven’t been using C or C++ for 10 years than those who have.
It is very nice to say that, in theory, a GC could work very well for performance demanding games. But until someone builds that GC, in an environment where everything else is suitable for games also, it is academic. We can't actually build a game with a theoretical ecosystem.
Of course, this is a theoretical conversation. My point is that you don’t refute the claim, “low latency GCs are suitable for game dev” with “I used a high latency GC and had a bad time”. Nor do you conclude that GCs inherently introduce latency issues based on a bad experience with a high latency GC. There is neither theory nor experiment that supports the claim that GCs are inherently unsuitable for game dev.
I never worked with Unity myself but I worked with people using Unity as their game engine, they all had problems with stuttering caused by the GC at some point.
You can try to search Unity forums about this subject, you'll find hundreds or thousands of topics.
What really bothers me with GC is that it solves a pain I never felt, and creates a lot of problems that are usually more difficult to solve.
This is a typical case of the cure being (much) worse than the illness.