Never completing query ending temp space error

Dear Team,

We have a procedure running in DEV instance that is failing within 5 minutes with the error:

"Unable to extend temp space", despite having 20 GB of TEMP space allocated.

It was executing insert statement, The execution plan indicates that a significant amount of work is being performed in a few operations, which is likely causing excessive TEMP usage.

At this point, we are unsure how to proceed with troubleshooting. Since the query is long, We have attached:

The SQL query
The execution plan

We would appreciate guidance on:

Identifying the operations responsible for high TEMP consumption
Understanding the root cause of the excessive resource usage