Hi there! My computer started dying when I used this template, but I thought it was my fault. After a few hours of effort, I found that rust-analyzer HATES flatpak-builder. It'll recursively search through all of flatpak-builder's files, making it eventually crash the system (or if you're lucky, just your editor).
Here's the thread about that. I just commented my "fix" so please scroll to the bottom if you wish to see more about that...
rust-lang/rust-analyzer#8161 (comment)