unicode characters don't work in nested dynamic routes

### Describe the bug

umlauts don't work when nested in a dynamic route e.g. [variable]/ö

### Reproduction

https://github.com/noahsalvi/kit-path-broken-repro

### Logs

_No response_

### System Info

```shell
latest
```


### Severity

blocking all usage of SvelteKit

### Additional Information

_No response_