My observation is that anything based on public cloud providers using their load balancers is basically using HTTP3 out of the box. This benefits people that us

My observation is that anything based on public cloud providers using their load balancers is basically using HTTP3 out of the box. This benefits people that use browsers that support this (essentially all browser and mobile browsers). And since it falls back to plain HTTP 1.1, there are no downsides for others. Sites that use their own apache/nginx/whatever servers are not benefiting from this and need to do work. And this is of course not helped by the fact that http3 support in many servers is indeed still lacking. Which at this point should be a strong hint to maybe start considering something more modern/up to date. Http clients used for API calls between servers that maybe use pipelining and connection reuse, benefit less from using HTTP3. So, fixing http clients to support http3 is less urgent. Though there probably are some good reasons to support this anyway. Likewise there is little benefit in ensuring communication between microservices in e.g. Kubernetes happens over http3.