After0e8e219d71/efb511a76d, memfile undo step is not used for writing the autosave file, instead regular file saving function is used (`BLO_write_file`). With that it is possible to compress the file when `G_FILE_COMPRESS` flag is set. As discussed in !132685, always compress auto-save .blend file irrespective of `USER_FILECOMPRESS` Pull Request: https://projects.blender.org/blender/blender/pulls/132685