Is it permissible for an employee who has not been assigned any tasks and is asked to wait to receive his salary for the period he did not regularly attend work, and what is the expiation for that?

Dear questioner, you are considered a private employee, and your services are due to your employer throughout your working hours. You must pay back the equivalent of the periods you were absent and return it to your employer, even if indirectly. If you are unable to do so, then spend it on public welfare and charitable causes.