The 7z archive is also used in the official Chrome installer. And e3kskoy7wqk just extracted it from the installer, you can check, download ungoogled-chromium_135.0.7049.41.1_installer_x64.exe and extract chrome.7z from it, the hash should match. Properly you should have extracted and re-archived, but with normal compression, format is not important in principle, everyone has some archiver to open any format.