You don't get feats while polymorphed
This spell transforms a creature that you can see within range into a new form. [...]
The target's game statistics, including mental ability scores, are
replaced by the statistics of the chosen beast. It retains its
alignment and personality.
Feats are part of a creature's game statistics (in fact, most of the time they are class features). As such, they are replaced with the creature's statics when you transform into the new creature. See this question for more details on what "game statistics" means.
Thus, none of your feats have any effect while in polymorph form.
The rule of thumb when you transform is that if it's not on the new form's stat block, you don't get it in that form.
Or as Jeremy Crawford has said:
You're playing with the stat block, not your character sheet. Set the latter aside.