Golden Rule: If Microsoft didn't release it, don't trust it. There is no community "recompiled" 64-bit version. The source code for SharePoint Designer was never open-sourced. If you absolutely need to use SharePoint Designer
This is the simplest, safest method.
For workflow design: Microsoft Power Automate Desktop
For master page editing: SharePoint Online Modern UI + PnP PowerShell
For data view web parts: List formatting with JSON + SPFxGolden Rule: If Microsoft didn't release it, don't trust it
If you need "workflows" (what SPD 2010 was great at), Microsoft Power Automate has replaced SharePoint 2010 workflows entirely.
If this is a technical blog or reverse-engineering post, it probably discusses:
