No. There aren't, I think.
I will add those tests.

There is an awful amount of noise in the failure logs, but there does appear to be a legitimate failure here.

I've fixed bugs.

I have a question about bool[]? Deserialize(ref MessagePackReader reader, MessagePackSerializerOptions options).
Where should I place the simd-accelerated deserialization helper code?
Append it to UnsafeRefSerializeHelper.cs or write another file such as UnsafeRefDeserializeHelper.cs?
The simd-accelerated deserialization helper code does not share any code with the serialization helper methods.

Where should I place the simd-accelerated deserialization helper code?

Given the length of the existing file, my vote is create a second file.

Do you want me to merge this as-is, or do you want to add the deserialization optimization to it first?

Ok.
I'll create another PR of bool[] deserialization with a second file.
Please merge this PR as-is.