Tried to run the benchmark on my laptop (with a Ryzen 5 3500U), got different results much closer to what I would expect normally:

==> Running benchmark for java_grpc_pgc_bench... Requests/sec: 25563.46

==> Running benchmark for cpp_grpc_mt_bench... Requests/sec: 31389.24

==> Running benchmark for dotnet_grpc_bench... Requests/sec: 25376.18

==> Running benchmark for go_grpc_bench... Requests/sec: 29158.60

==> Running benchmark for rust_tonic_st_bench... Requests/sec: 28120.25

Different images for the same language (java, rust, cpp) performed with similar if not worse results