What is the default isolation level in ef core 6 in BeginTransaction

Question

I have following code

using (var transaction = dbContext.Database.BeginTransaction())
{
//my code creating a temp table and inserting rows into it
transaction.Commit();
}
catch                
{
transaction.Rollback();
throw;
}

I want to know what will be default isolation level I'm trying to create a temp table in transaction and then performing some other queries and using that temp table in it. I want to know what will happen when different users will call this at same time. I'm creating temp table inserting rows into it and then using it in my query my query is just a select query.