Yes! It’s a single commit in our fork: Open the composer near the top like a dialog · mementomori-social/mastodon@d14b2dd · GitHub
It touches trigger.tsx and trigger.module.scss, and it cherry-picks cleanly onto current mastodon/mastodon main.
The commit itself only dims the background with 50% black. The blur and the darker background come from Mastodon Bird UI: mastodon-bird-ui/src/components/_modals.scss at 724cf08cb343a4cc0ac3b1b79c850a05096492a4 · rollecode/mastodon-bird-ui · GitHub
If you don’t run Bird UI, you can copy that one rule into your custom CSS once the commit is in.