Great to see a C# post on steem!
I think this way is a good way to do it, I'm using similar code since C# 6 was out :)

About performance, depending on your class and how it's used, this might even improve performance because less garbage collection is needed.
e.g. If you initialize a list in a constructor, but only 50% of those classes will ever use it. then those empty lists will require collection later on without providing a benefit.

Also if performance is a huge point, code like this might still be useful in combination with ObjectPool, Span/Memory or an self-upgrading structure like the StringValues class (one shared empty instance, when upgrades into a single, then into a multi value object) instead of calling "new List<>".

However, it always depends on the usecase and project :)

I think especially for newer coders or in parts that are exposed to 3rd party code (e.g. a plugin system), this might be a great pattern to reduce unintended null reference exceptions and improve reliability.