There are two cover letters.
The one you send: “I’m excited about this opportunity. My experience in [industry] has prepared me to contribute to your mission. I’m a collaborative leader who thrives in ambiguity.”
The one you write at 2 AM: “I was fired for telling the truth. I’m overqualified, under-settled, and I will outwork anyone you’ve ever hired. But you won’t call me back because my LinkedIn has a gap and gaps scare people who’ve never had one.”
The acceptable performance of job seeking requires you to pretend the thing that happened didn’t happen. Gratitude. Growth narrative. “What I learned from the experience.” You learned that loyalty is a one-way street and HR is not your friend. You can’t put that in a cover letter.