Where does a single-line value render inside its box?

document 55647   dpi 144   page 1 1224x1584 units
   probe field h=22u (11.0pt)  w=715  TEXT.1.0
   probe field h=21u (10.5pt)  w=716  TEXT.1.1.1.0
   probe field h=20u (10.0pt)  w=323  TEXT.1.1.1.1.1.1.1.1.1.1.1.1.0
   probe field h=25u (12.5pt)  w=504  TEXT.1.1.1….1.2.1.1.1.1.0.0.0.1.0
   probe field h=34u (17.0pt)  w=506  TEXT.1.1.1….1.2.1.1.1.1.0.0.0.1.1
   probe field h=29u (14.5pt)  w=504  TEXT.1.1.1….1.1.1.1.1.1.1.1.1.1.0
   wrote anchor_before.pdf
   trimmed 6 field(s) by 10u and saved
   wrote anchor_after.pdf

Now measure both files with pypdf.

cleaned up: deleted document 55647