Microsoft doesn’t support Windows 7 either so it’s not surprising that Obsidian doesn’t.
The last release that works on Windows 7 is presumably the one you upgraded from. You can download old releases from Releases · obsidianmd/obsidian-releases · GitHub .
I would have sworn the Electron update was mentioned in the update notes because that’s why I reinstalled instead of just using the in-app update, but you’re right — it’s not in the announcement here. I’m not sure where I saw it.
Moved from Bug Reports to Help because it’s not a bug (and you didn’t follow the bug report template anyway).