'School librarianship' has a different mission than that of public librarianship. Often, school librarians fail to prepare K-12 students "to become critical thinkers, avid readers, skillful researchers, and ethical users of information." (AASL, 2010) By failing to live up to this mission, school librarians often seek to adopt the mission of public librarians. (This, in my opinion, is also a failure of graduate preparation programs preparing 21st century information professionals. One-sized curricula does not support all types of librarianships.)
What is the difference in the stated missions? Primarily, school librarians are held accountable for K-12 learning; while public librarians are not assessed/held accountable for how well learners, adopt, and use information being shared (i.e., vetting credible information sources; etc.).
The current pandemic and the widespread use of virtual learning has exposed the failure of both public and school librarians to prepare learners (young and older) to navigate social media, disinformation, and alternative facts. And, failures/limitations of some graduate preparation programs.