Is the Dad still alive? That would be useful to know. Having a W2:

Dad still works, and the trust also exists. The type of trust matters, by the way.

Or, Dad died in that year, and the W2 is for work that year.

Or, Dad died in the prior year, but the employer had a follow up responsibility, and the W2 is after the date of death. The W2 is in error?

See this:

https://www.irs.gov/pub/irs-utl/decedent-tax-guide.pdf

"If payment was after the year of death, the employer should not report it on Form W-2, and should not withhold Social Security and Medicare taxes. Whether the payment was made in the year of death or after the year of death, the employer also must report the payment to the estate or beneficiary on Form 1099-MISC."