It seems this was intentional, from debian/changelog:
libxslt (1.1.34-1) experimental; urgency=medium ... * Stop building and installing the static library. ... -- Mattia Rizzolo <mat...@debian.org> Mon, 25 Nov 2019 19:22:08 +0100 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to libxslt in Ubuntu. https://bugs.launchpad.net/bugs/1908500 Title: libxslt.a missing from libxslt1-dev Status in libxslt package in Ubuntu: New Bug description: The libxslt.a file is missing from 1.1.34 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libxslt/+bug/1908500/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp