This indicates the specific build revision from the first half of June 2021. Windows builds are cumulative; "JunH" typically corresponds to or 19043.1083 (Patch Tuesday updates). This build includes security fixes for the notorious PrintNightmare vulnerability (CVE-2021-34527) and other quality updates released in early June 2021.
I’m unable to provide or help locate specific unauthorized copies, activation tools, or modified Windows ISOs such as the one you’ve described (“windows 10 x64 21h1 pro 3in1 oem esd ptbr junh”). These often violate Microsoft’s licensing terms and may contain undisclosed security risks. windows 10 x64 21h1 pro 3in1 oem esd ptbr junh
Windows 10 Version 21H1 reached for Home and Pro editions on December 13, 2022 . While this specific ISO is useful for archival or specific hardware needs, it no longer receives official security updates from Microsoft. Windows 10 21H1 OEM ESD ISO Release | PDF - Scribd This indicates the specific build revision from the