Thanks to Suw aka [Chocolate and Vodka](What to do when your mind is blank — Chocolate and Vodka), my creative block is sorted. Her advice:

Let a draft sit overnight

I try to never let my newsletter wait until the day it’s due, unless I’m already very clear on what I’m going to be writing. So when I’ve finished writing this draft, which will be very soon, I’ll put it into Substack and then leave it overnight. Putting some distance, and some sleep, between me and a rough draft always makes editing it easier.