There is currently an EU member challenging the concept of European law’s primacyThat's a charitable phrasing. As per Protocol 2 on the functioning of the European Union, article 8 [2]:
The Court of Justice of the European Union shall have jurisdiction in actions on grounds of infringement of the principle of subsidiarity by a legislative act, brought in accordance with the rules laid down in Article 263 of the Treaty on the Functioning of the European Union by Member States
What Poland did was declare nationally (government, and then a national court) that the EC was infringing on its sovereignty (principle of subsidiarity). But as the above text says, national governments don't have jurisdiction when it comes to matters questioning the primacy of European law.
[2] https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:12...