In DEVPROD-11649 we modified the string equality function in the fuzzer to attempt to coerce strings to numbers and use an epsilon based equality to deal with floating point precision differences that can leak to strings with the $toString operator.

A concern that this approach does not address is if floating point numbers end up as group keys. One idea to catch such cases is to add test-only logging to the server which logs queries that may result in non-deterministic result sets (for example group keys that are objects that don't have a field order, or floating point numbers). The fuzzer test runner can then consume these logs and ignore result set differences.