SPARC (Scholarly Publishing and Academic Resources Coalition) has posted on its website information on how a library might push back on vendor confidentiality clauses. As SPARC notes, those confidentiality clauses, and non-disclosure agreements, help the vendor and not the library. If a library must keep the vendor contract confidential, then the vendor is under no pressure to treat every library equitably. SPARC notes that some libraries may be governed by sunshine laws, while others may reject confidentiality as a matter of policy.
If pushing back on non-disclosure agreements is of interest to you, then SPARC's information will give you thoughts about the actions you might take.