I'm responding as a professional pianist.... There are a couple of variables that come into play when listening to someone play a piece of music. One is that different publishers use different editors when producing sheet music. So, even from the earliest source material that can be found, editors may take liberties in regards to dynamics, articulations, and tempo. Also, the player will approach a piece with their own sense of musicality. Even if you handed two pianists identical sheet music, there would be variations in how they were performed. I suppose that's not a super helpful answer, but I guess one could go down a rabbit hole and find out how close the sheet music we have today matches the originals, if they still exist. I would assume that the players are doing their best to be true to the source material, based on what we know about music of the era, but honestly, some take great liberty. I remember doing an exercise in school where we each had a sheet of paper, and the teacher read aloud a list of instructions like, "draw a circle in the upper right corner", and so forth. Even though we all received the same set of instructions, every paper looked different. It's kind like that.

Spotify's collection of recorded classical music is vast, with many of the best ever recordings of pieces on there. Some famous pieces, such as beethoven's works, have 100 different versions.

It can be worth googling the piece, to see what comes up about it, and its history, and the different interpretations.

In terms of the range of difference between what the original might have sounded like, vs a modern interpretation, you could check out the Voices of Music version of Pachelbel's Canon, vs say the Neville Marriner version. The VoM version is performed on vintage instruments, and they try to adhere to what their belief of how it would have been performed, whereas Marriner's version is the more familiar version to our ears.

This is probably at the more extreme range of variance in interpretation, as the piece is so old, and little of Pachelbel's music survived. Interpretation differences for something like Paganni's work would be more subtle.

But what's most interesting, is how different interpretations can be of a composers works while they are still alive. Recordings exist of Gershwin's Rhapsody in Blue, featuring Gershwin himself, in 1924 and 1927.

https://youtu.be/VGvuUOtHGkk

https://youtu.be/PA3ryT2HJK4

There are some quite noticeable differences in interpretation, even between these two performances.

I don't think Spotify does their own recordings.

They do offer various recordings of performances by various orchestras throughout the world. Some aim to be as authentic as possible in terms of using original instruments, and so forth, but that's just not realistic usually. Most Oboe players don't have an oboe dating back to the 16th century, for example. I guess my overall point is, we don't know. We don't have recordings from four hundred years ago to compare modern performances against.

Eh?