It seems that Go's behavior when casting Positive Infinity to uint32 is architecture specific. This causes theApproximatedSize calculation to return an inconsistent value between architectures.

If you run this:

saturatedBloom := bloom.FromWithM(bitset.New(10000).Complement().Bytes(), 10000, 4)
fmt.Println(saturatedBloom.ApproximatedSize())

In amd64, it prints 0, while if you run it on arm64, it prints the max value for uint32.

For a smaller example:

fmt.Println(uint32(math.Inf(1)))

Is equivalent.

I'd expect a saturated bloom to return a very high number and not zero, so I'd propose checking first for a saturated bloom and returning max uint32 explicitly.

See: golang/go#56023