Cannot mainpulate time values based on HH:mm:ss format

I have values like time values like so `08:00:00` and `22:00:00`, following **ISO 8601** standards and how postgres accepts "time" types.

The issue is I cant find a means of manipulating values like so using dayjs. For instance I cant get the difference between 2 time values using the format. The code block below return **NaN**, when attempting to format the time is return invalid date as well.
```
const operationalHours: number = dayjs("22:00:00").diff(
"08:00:00",
"hour",
);

const format = dayjs("22:00:00").format("HH:mm:ss");
```
I cant change how the time is set, is their a workaround for this?