The $3,367 on Line 13 of Form 8889 reflects the amount you could contribute out-of-pocket after the employer contribution of $4,150. Added together, you get the $7,517.
Even though only $150 of the $4,150 was actually contributed by the employer, the entire amount is reported on your husband's W-2 as Code W because it was funded with pre-tax dollars. Whether it was an employer or employee contribution is irrelevant.
Your husband could still contribute $3,367 to his HSA before hitting his max contribution for 2021. If you open an HSA in your name, you can still contribute to it, both in 2021 and going forward. This is assuming you are still covered by the family HDHP and not yet eligible for Medicare. You would have to enter that separately as your own contributions.
@Cindy77
