Is it true if you make the wrong choice after istikhara Allah will prevent it from happening since you asked him in the dua to keep it away that “thing” from you if it is bad for you?
There is no such guarantee and we bear the responsibility of our own choices fully. What matters is that we should stay in line with the Divine good pleasure at all times in order to see clearly when making istikhara to Him and istishara to trustworthy advisors. At that time there is no wrong choice because Allah Most High does not disappoint those who do their best.
Hajj Gibril Haddad