Spring Boot 3.0.4 is available now!

Spring Boot 3.0.4 is available now!

☆ - Great. Would you recommend to switch to it for a project that is currently on 2.7?

As always, it depends but in general, definitely! 😎 
There are so many good things in it! 
Also, you need to do it eventually since 2.7.x will not be supported starting from November:

☆ - Do you (or someone) know if Spring Boot 3 is supported by Instana (the RedHat APM) ?

As far as I know yes but I think it can also scrape the Prometheus endpoint and receive spans in the Zipkin format 
so even if there would not be separate support for Boot, 
I assume your Boot app should be able to publish metrics and spans out of the box.