Release Post 13.9 Retrospective

Release post MR: !73764 (merged)

Please add your feedback by 2021-02-23. Thank you!

Note for release post team (release post manager, TW lead and Messaging lead): For items you want to cover during the live retro, please add the ⭐ emoji.

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Start your comment with an H2 heading which will be used as its title, and add the appropriate icon the front of it to indicate which category it falls under:

• 👍 What went well?
• 👎 What didn't go well?
• 💡 What can we improve?

Example:

## :thumbsdown: Inconsistency of feature names capitalization

Create individual comments for every entry so that each item can have its own thread. Then, each thread will get an **Action: @mention** for resolution tracking for the release post manager. As we all complete our assigned actions, we should put a ✅ on the initial comment of the thread to indicate it's done.