GraalVM comes with its own JIT the Graal Compiler [1] which I believe was what metadat was talking about. You are probably thinking about the native image generation which can cause issues with reflection and other dynamic constructs.
Also, reflection is supported in AOT mode. The analysis, however, does require reachability metadata in some cases. In the best case, libraries provide and maintain appropriate configuration for this. Reachability metadata can also be shared via https://github.com/oracle/graalvm-reachability-metadata.
[1] https://www.graalvm.org/22.3/reference-manual/java/compiler/