Can a witness testify that they fear retaliation for testifying?

As the trial court also pointed out, the reasons a witness fears retaliation are also relevant to assessing the witness's credibility, but because the prejudicial effect of such evidence may outweigh its probative value on the credibility question, such evidence is admissible "within the limits of Evidence Code section 352." (People v. Stewart, supra, 33 Cal.4th at p. 492, fn. 28.) But this does not mean that a witness's testimony that he or she fears retaliation for testifyingwithout any explanation of the reasons the witness fears retaliationwill always be unduly prejudicial.