In which table does Postgres records the savepoint name, when we define a savepoint in a transaction?

Question

I always found a blocking query in the database is "ROLLBACK TO _EXEC_SVP_0x16539e0", and I suspect that the database is not able to find the savepoint name, due to which there is no end to a transaction.

So, I want to know if there is any way that I can find all the existing savepoint names that are active.