It's overwhelming, isn't it. You feel like you're supposed to have this endless energy to do something outside of your comfort zone, and as you hit more and more roadblocks, the "resistance" to "doing" becomes stronger and stronger - I mean, why keep doing it if it's just going to be so difficult, right? I'm definitely projecting in this response to your post because as someone who stepped away from Unity and game dev for a while, I'm finding I'm pretty rusty in ways I didn't think I'd be and have been struggling. So, you can look at it a few different ways:
1- Give yourself permission to fail to submit anything. You have an idea about what you want to do and it might take you longer than the game jam period allows. However, you will still anchor a lot of things into memory and your game development skills will be better. Plus, you can still complete whatever you started, add it to your Itch account as part of your portfolio, and you'll be all the more prepared to join another jam and do better.
2- Give yourself permission to fail to create the game you wanted to, but commit to submitting something. This will involve stepping back, re-scoping your idea, and still be able to submit the game and get some feedback - you'll probably get more people playing it and giving feedback in the midst of the post-jam activity than finishing it in another month. Properly scoping a project is a huge skill that will be incredibly valuable for you to develop for future jams and even commercial projects. FYI, sometimes you lose energy toward an idea because you're not really into it, too - so you can use re-scoping to re-conceptualize the project entirely. At this point, you still have like a week.
3- Give up... for now. Maybe now isn't the time - maybe you're really distracted with other things or maybe you don't have enough of whatever it takes to "fill your cup" with what it takes to get even a small, mediocre game submitted. Game dev isn't for everyone at all times - maybe you need to build more skills and get some other small game projects completed on your own before tacking a jam.
Personally, I left the jam and just rejoined - this past weekend wasn't what I had hoped it would be at all and had the disappointing sense that I wouldn't be able to submit something I'd be okay with. However, after sleeping on it, I'm going to go with #2 above and just get something done - probably with a strong focus on a particular thing that I think I can do well, like lighting and post-processing, something visually pleasing but not necessarily as fun and riveting as I originally wanted to. I'll take submitting something as an accomplishment and look forward to adding a focus to my game that involves something interesting to me to learn or develop further.