Techniques are provided for mirroring objects between object stores hosted by cloud providers that could have different data layout requirements. An object may be stored within an object store that supports a unified object format where the object is capable of storing compressed data. The object may be mirrored to a destination object store that may also support the unified object format or to a destination object store that does not support the unified object format. If the destination object store does not support the unified object format, then slot header metadata within the object is used to decompress the data within the object into an uncompressed format. The data is packaged from being in the uncompressed format into a fixed offset format supported by the destination object store to create a mirrored object that is stored into the destination object store while retaining compression of the data.