I don't know if this is a bug, but with the very latest Lilypond
versions (2.25.+) the distance between the top margin and the title
text does not match the value I specified, in this case 5
millimeters. [...]
Have you looked into the 'changes' file from LilyPond? The first
entry for the 2.25.x series is
Margins are now wider by default following the general layout of
several publishers (and the recommendations of Elaine Gould).
In order to switch back to the previous settings (e.g., to keep the
same layout when upgrading an existing score to version 2.25.14),
add the following code:
```
\paper {
top-margin = 5\mm
bottom-margin = 10\mm
top-system-spacing.basic-distance = 1
top-markup-spacing.basic-distance = 0
left-margin = 10\mm
right-margin = 10\mm
inner-margin = 10\mm
outer-margin = 20\mm
binding-offset = 0\mm
}
```
It seems to me that you should adjust the `top-markup-spacing` value
in your settings.
Werner