The upstream bug has been closed because Prusa Slicer no longer has USB control capabilities.
Are you sure this is related? Your upstream bug[1] is still open last I checked.Also, prusa-slicer 2.7.1+dfsg-1 still depends on libbgcode[2], so it will still FTBFS on all big endian archs and block migration due to the missing s390x build.
[1] https://github.com/prusa3d/libbgcode/issues/47[2] https://salsa.debian.org/3dprinting-team/slic3r-prusa/-/blob/master/debian/control?ref_type=heads
