int?? magic
int8 Major { get; set; }
int8 Minor { get; set; }
int8 Unknown { get; set; }
int8 SignatureType { get; set; }
int32 Offset { get; set; }
int32 Length { get; set; }
int64 Manifestid { get; set; }
int32 DecompressedLength { get; set; }

actual arrangement=

[long] magic
[int]  content ???
[int]  compressed size
[long] manifestid - C7 06 88 36 C6 31 12 F7 - LE
[int]  uncompressedSize 
[int]  zstd compression