You are nearly correct but you are subtly misunderstanding how the precedence rules work.
Compare these two cases:
int t1 = 5;
int t2 = t1 + (++t1);
System.out.println (t2);
t1 = 5;
t2 = (++t1) + t1;
System.out.println (t2);
The result is:
11
12
The precedence does indeed say to evaluate the ++ before the +, but that doesn’t apply until it reaches that part of the expression.
Your expression is of the form X + Y
Where X is t1 and Y is (++t1)
The left branch, i.e. X, is evaluated first.
Afterwards the right branch, i.e. Y, is evaluated.
Only when it comes to evaluate Y the ++ operation is performed.
The precedence rules only say that the ++ is “inside” the Y expression, they don’t say anything about the order of operations.