Please check the attached AI which was saved from an SVG exported from Avid Sibelius 2021.2 on macOS 11.2.1 — in Finder and Spotlight the preview is correct and corresponds to what was in the source program (Sibelius).
Opening the file in Illustrator makes all text objects which were in Academico font, Regular weight, become Italics weight.
Opening the file in Affinity Designer doesn't show this particular problem.

I cannot attach the SVG so I'll attach the AI.
I hope you can investigate it in the same way.
This is the Dropbox link to the SVG: https://www.dropbox.com/s/l4aja38o3iu0txu/bach-inventio4_0001.svg?dl=0