I have so much trouble thinking of new project ideas. I want to build a project both in Rust and Go to see which I like more, but I can't think of anything. How do you guys do it?

Personally just think of things that I need, stuff I want to learn more about, or tasks that need automated.

Rewrite an old project.

It doesnt have to be anything particularly useful as long as it does SOMETHING.
I wanted to practice using AWS Lambda and DynamoDB so I built a basic serverless app which allows certain users to securely upload files to an S3 bucket.

Not very useful since Im the only one with access to the bucket, but it was still fun to build and it served its purpose perfectly.

You could try some coding challenges. Something like AdventOfCode.com. I know it's not advent time now, but I love the puzzles.

dunno, does it help to think about what you generally want from a project?
like are you more hyped the more stupid and useless the idea is?
or are you more for stuff that makes your live easier (if you don't count the work you need to create and maintain it)?
would like some parody? (fuck of as a service, noCode, ...) some homage (to some movie, manga, book, ...)?

personally on my list is to code some simple games (tetris, minesweeper, asteroids,...) with low GUI and then maybe a NN to play it