What I could observe so far:

After updating trunk to 0.21.6, all styles used in were somehow not applied. I can observe the following errors in developer tools, when enabled in debug mode:

Refused to load http://localhost:1420/styles-8594f9560b2c9a3f.css because it does not appear in the style-src directive of the Content Security Policy.

Steps to reproduce:

cargo install --locked trunk@0.21.6 --no-default-features --features=rustls
cargo install --locked tauri-cli
cargo install create-tauri-app --locked
cargo create-tauri-app
cargo create-tauri-app -m cargo -t leptos -y my-app
cd my-app
cargo --locked  tauri dev

Expect something similar to the following screenshot to be shown:

Actual result:

The issue is reproducible on linux and on windows.

In the meantime I went back to 0.21.5 which works fine, and doesn't cause those issues.