Don't worry, it's not :)
The full source is available on GitHub if you'd rather build it yourself : https://github.com/charles-l/32bitjam (it's created with all open source technologies too: Python, Nuitka, and raylib).
Hmm... I've gotten a warning on my game's exe and a few other jam submissions, including Unity builds which is annoying since it's the most popular engine out there. I've been working around Window's defender (on Windows 10), by clicking "More Info > Run anyway" when I get the blue "Windows protected your PC" popup.
But if it's not even letting you download the file that's either the browser (maybe try a different one? I'm using Chrome?), or some new "security feature" in a different version of Windows that I haven't come across yet. I've used this same tech stack in game jams before without issue, so this must be new 😞
I'll take a look at some other Python distribution options, but I'm not sure if there will be anything that will placate Defender since it works off of pretty naïve pattern matching. If you build a large enough binary with enough dependencies in it (like a game), you're bound to include some benign functionality that was flagged in a virus at some point that Defender includes in its pattern library.