And quoting web-sys d/changelog:
rust-web-sys (0.3.35-1.1) unstable; urgency=medium
* Non-maintainer upload.
* Reduce the Provides field to the 2 values actually used in the Debian
archive so that we don't break reprepro with a field of more than
256 Kb and so that we are below the new DAK-enforced limit of 64 Kb.
-- Raphaƫl Hertzog <hertzog at debian.org> Fri, 17 Jan 2020 10:17:12 +0100
web-sys provides an insane number of features, debcargo's workaround for
the lack of version range dependencies in dpkg blows that up even more.
So we can't ship all the provides that debcargo generates while staying
within the realms of what the archive will allow.
But that doesn't mean we can't add back provides that we actually do
want/need for reverse dependencies.