The sequence "4C.7z" is simply a coincidental result of the encoding process. It is not a real 7-Zip file, nor is it a hidden "leaked" archive. Where You’ll Find It

It is part of the binary-to-text encoding used to include graphics or formatted documents within a plain text submission.

It appears in thousands of documents, such as Form 424B2 or FWP filings.

In UUEncoding, each line typically starts with a character representing the number of data bytes on that line. "M" is ASCII 77, which corresponds to a line length of 45 bytes—the standard for many older encoding systems.

You can find these strings in the raw .txt versions of major corporate filings: