I think the JVM tests should have been executed with the same amount of heap allocated for each platform in order to get the internal dynamics/heuristics of the JVM to be comparable. IMHO all JVM tests should have been executed with -Xmx 7G (8 Gigs maximum as per the M1 MacBook Air minus a little something for the OS and the system buffers)
Still, I'm impressed with the Apple silicone.
The reason why I'm suggesting to have the same heap size for the benchmarks is that the maximum heap size is the single most important (tuning) setting for the JVM. Based on this setting the VM sizes its internal data structures and adepts its behavior.
Also, garbage collection times are typically* dependent on the size of the heap. With most* garbage collectors collecting a 32gb heap takes longer than collecting a 8gb heap. If the workload of the benchmark allows for the heap to be used entirely, then garbage collection overhead is directly related to the heap size.
* unless a "big heap" garbage collector like ZGC or Shenandoah is used
Heap resizing has a much bigger impact on performance than garbage collection.