How to find a backup task by percentage complete

Here I am showing how to check backup task completed by percentage.

SELECT query = a.text, start_time, percent_complete,
    eta = dateadd(second,estimated_completion_time/1000, getdate())
FROM sys.dm_exec_requests r
    CROSS APPLY sys.dm_exec_sql_text(r.sql_handle) a
WHERE r.command LIKE 'BACKUP%'

Other Refrences:

SQL Server find database without backup from a given date

Backup History using TSQL

Restore database in SQL Server TSQL Statement