The actual cause of transaction log full under below scenario

In one of the instance, it shows >The transaction log for database 'DB' is full. To find out why space in the log cannot be reused, see the **log_reuse_wait_desc** column in **sys.databases** The instance has at least 100g hard disk empty storage and the transaction log allowed 2,097,152MB (2T) to grow, growth rate at 10%. The database recovery mode is FULL (at least it displays FULL in the SSMS) In this case, what can cause the exception of full transaction log? When the transaction log have enough physical storage to grow and the log size is not bigger than the upper bound