steve rogers is an excellent liar when it comes to achieving his goals (which thankfully, are usually very goodnatured and just, based on his personality). heās also a great liar when it comes to protecting people he cares about and even himself (even too good of a liar in that case, ie his mental health or not acknowledging his personal struggles in favor of a chin-up, brush-it-off, donāt feel bad for yourself, hardluck attitude obviously borne from his preserum life).
steve is a shit liar when he doesnt have a cause to defend or a reference point. this speaks to his inherent goodness (we are supposed to juxtapose this to Nat, who lies so easily she forgets herself and searches for Steveās approval).
steve doesnāt lie for lyingās sake, instead he uses lying to manipulate assholes or unfair situations to his advantage. therefore, the act of lying becomes essentially good and is therefore secondnature to him and can come off very much like the Truth.
itās worth noting that itās in CATWS that steve comes off as the worst at lying - the film directly following TFA which is meant to display how utterly unmoored and overwhelmed steve is by the 21st century.
the whole movie builds up on this feeling of disorientation, this lack of personal narrative, this situation where steve discovers he is being used and played for a fool by the very country he personally saved, a country which has turned into something he does not like or recognize.
the point of CATWS is that steve learns he cant and wont tell someone elseās lies or serve anyone elseās agenda (a prelude to his CACW arc).
this theme of lies and lying and who to trust/not trust very starkly plays against the relative āeveryoneās on the same side against evilā wholesomeness of TFA.
this theme of CATWS it is reflected in Natashaās paranoia and mistrust (I only act like I know everything, Rogers", āIf it were the other way around and it were up to me to save your lifeā¦ā, āthe truth isnt all things to all people all the timeā). it is reflected in Furyās arc which eventually leaves him dead (āEars Everywhereā). it is reflected in Sharonās spy role and also in Peggy herself (āAunt Peggy kept a lot of secrets, I didnāt want her to have one from youā).
and of course, this journey of lies and secrecy and Ultimate Truth meets its emotional crux in Steveās final altercation with bucky. steve is desperately looking for the truth in anything, and Buckyās eyes glinting in horror and realization at the man under him as the world comes physically (and emotionally) crashing down around them?
Steve and Bucky find their truth and peace in each other, yet again. Just like Steve couldnāt lie to Bucky in TFA (āYeah because you got nothin to proveā) he canāt lie to Bucky in the present. familiarity at last. And Bucky canāt lie to him. Even through brainwashing and pain and suffering. nothing can hide Bucky from Steve. Til the end of the line.
It is here we see one thing become very clear: Bucky becomes Steveās truth, and vice versa. Thus the events of CACW. They keep one another close, and they wonāt become unmoored again.
Steve is a great liar in CATFA, a piss poor liar in CATWS, and a bold-faced FUCK YOU ALL in Infinity War. He doesnt have to lie anymore: he has all the personal power, all the physical power. He doesnāt need to skirt by as a 95lbs disabled man in the 30s, and is no longer bamboozled by the dishonesty of the 21st century.
He doesnāt have to lie anymore. But he will, if he deems it necessary. but he becomes more discerning and wise with it. he doesnt need to whip out BS like in the 30s, but he doesnāt want to lead or become part of the unhinged world he witnessed in CATWS. he wants something better and more for everyone, including himself. which leads to IW Steve.