Formatter Discrepency

If in my config/main.php I use

'timeZone' => 'America/Montreal',

and in my index.php view file I use

\Yii::$app->formatter->asDate($model->StartDt, 'M/d/Y');

I get 3/17/2020

Yet, if my config/main.php uses

'timeZone' => 'EST',

then my index.php view returns

3/16/2020

EST = America/Montreal, no?

I should add that the database value is ‘2020-03-16 23:00:00’

Shouldn’t it be EDT now?

https://en.wikipedia.org/wiki/Eastern_Time_Zone

Not sure.

EDT and EST both work, but I don’t understand why America/Montreal or America/New_York do not since they are both EST/EDT.

Yet, even using America/Montreal or America/New_York, the following works fine

\Yii::$app->formatter->asDateTime($model->StartDt . Yii::$app->getTimeZone(), 'M/d/Y HH:mm');

If my default config/main.php specifies a timeZone/defaultTimeZone, then why would adding it specifically to the asDate/asDateTime functions make any difference? Should that not already be the case since it is my default?