[Kaijo]

To give an example to further illustrate answers you've received. In the 1800s it was common to produce heavily editorialized volumes of Bach, Scarlatti and other baroque keyboard works, with tempo and dynamic indications, written-out ornamentation, phrasing and articulation marks, pedalling, and other directions that would have been a relatively alien language in the actual autograph and early editions. These were much more reflective of (romantic) performance practices of the day than of the original period. While much of it could be taken as potentially interesting suggestion about interpretation on modern instruments, it gets hopelessly muddled when the score fails to distinguish between what content is the editors' vs. the composer's, as they so often do. Something like this of Bach's C major prelude from The Well-Tempered Clavier, book 1, shows basically all the different kinds of unwanted editorializing I described: https://imslp.org/wiki/File:PMLP05948-WTC_Mugellini_No._1-12...

Compare that with: https://imslp.org/wiki/File:PMLP05948-WTC_1_No_1-12.pdf

A modern Urtext edition would also include detailed information about which manuscript and early edition sources it was prepared from, and any unresolved or variant readings between these sources, with performance suggestions (apart sometimes from fingerings) relegated to supplementary notes that are clearly written by the editors and not the composer.