A larger 7z archive does not by itself mean files have been lost or damaged. Check that it contains and recovers the intended files. If the archive meets your storage or transfer needs, there is no need to tune its sorting order solely because another copy is smaller.

Check the files before comparing sizes

Keep the original source files. Extract the archive into a separate empty folder so you do not overwrite them. Compare the recovered relative paths, file count and sizes with the source. For important material, use a byte-for-byte or file-hash comparison too: matching names and sizes cannot prove that the contents are identical.

If extraction reports an error or the comparison differs, preserve the source and investigate the archive's input list and extraction result. Recompressing with a different sort order is not a remedy for a missing input file or damaged archive.

Why sorting can change compression

7-Zip's official FAQ explains that solid 7z archives have defaulted to name order since version 15.06; earlier releases used file-type order. The order can affect compression, particularly when the dictionary is smaller than the complete input set. Neither order is universally best.

Optional: compare sorting when size matters

If you need to reduce a verified archive for a size limit, create a separate comparison archive from the same unchanged files. Keep the format, compression level and dictionary settings the same. In the Add to Archive window, the Parameters field accepts qs to select type order.

Keep both archives outside the source folder. Compare their sizes, then verify extraction of the alternative before choosing it. The FAQ also notes that unusual file order can slow some HDD operations, so weigh a smaller file against the recipient's use. Keep the originals until the required copy has been verified and your backup arrangements are satisfied.

Source: 7-Zip: archive size and sorting FAQ.