Does a court err by instructing a jury that a plaintiff must prove that retaliation is 'the' but-for cause of the adverse action, rather than 'a' but-for cause, as this Court's precedents clearly state?

Question presented The plaintiff in a Title VII retaliation case must “establish that his or her protected activity was a butfor cause of the alleged adverse action by the employer.” Univ. of Texas Sw. Med. Ctr. v. Nassar, 570 U.S. 338, 362 (2013). Does a court err by instructing a jury that a plaintiff must prove that retaliation is “the” but-for cause of the adverse action, which implies a sole-cause standard, rather than “a” but-for cause, as this Court’s precedents clearly state?