HITMAN 2 doesn't work

Did you get it from Humble Bundle? If so, you can contact support there for a different key.

See https://www.steamgifts.com/discussion/4V3Cy/humble-bundle-april-2020-humble-choice-5 for the region locks. You should be able to know which one from your friend's country.

TLDR:
China

LATAM/India - Bahamas, Panama, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Venezuela, Colombia, Guyana, Suriname, French Guiana, Brazil, Peru, Bolivia, Paraguay, Uruguay, Argentina, Chile, Ecuador, Antigua and Barbuda, Barbados, Dominica, Dominican Republic, Grenada, Equatorial Guinea, Haiti, Jamaica, Saint Kitts and Nevis, Saint Lucia, Mexico, Trinidad and Tobago, Saint Vincent and the Grenadines, India

RU/CIS - Russian Federation, Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Republic of Moldova, Tajikistan, Turkmenistan, Uzbekistan, Ukraine

Turkey customers should receive a ROW key but instead receive a key that they cannot activate (either the LATAM/India one or the RU/CIS one listed above). source

Everyone else: ROW

Why is your account showing as 'permanently removed' on steam trades? This is first i have seen so i would like to know.

its probably for eu or na since the most of hb keys are if restricted are from those countries

so you should change you region country using a vpn wont work cause it should be activated on those regions
i mean if all your other games are open-region

thats what you can do , since you dont know anything about the key but you should ask from him first maybe he knows

I may be able to help you with this. you can add me if you want.