Svelte 5: <svelte:element> not working with custom html tags

[adamspagge]

Describe the bug

svelte:element doesn't work properly with custom elements when using Svelte 5. The element is rendered correctly, but the necessary unique class name is not added thus the scoped css styles are not working. The example is working fine in Svelte 4.

Example with <svelte:element this={"custom-element"}></svelte:element>

Reproduction

Svelte 5 REPO

Svelte 4 REPO

Logs

No response

System Info

System:
    OS: macOS 14.5
    CPU: (8) arm64 Apple M1
    Memory: 72.89 MB / 8.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 21.4.0 - ~/.nvm/versions/node/v21.4.0/bin/node
    npm: 10.2.4 - ~/.nvm/versions/node/v21.4.0/bin/npm
    pnpm: 9.6.0 - ~/Library/pnpm/pnpm
  Browsers:
    Chrome: 127.0.6533.89
    Safari: 17.5

Severity

annoyance