The problem does not appear if the cairo backend is used, see
https://gitlab.com/lilypond/lilypond/-/merge_requests/853.
>>>
>>> This is good news!
>>
>> When copying and pasting from a PDF generated using cairo backend,
>> some characters turned into similar but different characters.
I recently updated lilypond from 2.18 to 2.22. Since then the rendered
svg files differ from the pdf files. The fonts used in title, composer,
poet, lyrics change the distance of staffs so that a song that is
rendered to one page in pdf, is rendered to two pages in svg. In
lilypond 2.18 pdf
>>> The problem does not appear if the cairo backend is used, see
>>> https://gitlab.com/lilypond/lilypond/-/merge_requests/853.
>>
>> This is good news!
>
> When copying and pasting from a PDF generated using cairo backend,
> some characters turned into similar but different characters. The
>
