What is the test for overturning a conviction on the grounds that the identification procedure was unduly suggestive?

Moreover, there must be a 'substantial likelihood of irreparable misidentification' under the '"'totality of the circumstances'"' to warrant reversal of a conviction on this ground." (People v. Cunningham (2001) 25 Cal.4th 926, 989-990; see also People v. Clark (2016) 63 Cal.4th 522, 556-558.) "A claim that an identification procedure was unduly suggestive raises a mixed question of law and fact to which we apply a standard of independent review, although we review the determination of historical facts regarding the procedure under a deferential standard." (People v. Clark, supra, 63 Cal.4th at pp. 556-557.)