If I have tag DELTAG() with expression DELETED() and try to reference it in SQL, my optimization gets affected. How do I use it correctly?

SELECT anyfield;
FROM T1, T2;
WHERE T1.field = T2.field;

Shows full optimization for both tables with SYS(3054)
If I try to use:

SELECT anyfield;
FROM T1, T2;
WHERE T1.field = T2.field;
AND NOT DELETED();

my optimization gets cut back to partial for T1 but remains full for T2. I have the DELTAG in both tables using the same expression.