Gutenberg works a bit different from the classic editor.
Actually it saves the values(layout) in the DB, and it’s picking the old layout. It just needs a refresh.
Just follow these steps:
1. Go to Edit Post
2. There you’ll find the message “The block contains unexpected or invalid content.”
3. On that block, click the three dots
4. Then click “Attempt Block Recovery”
5. There you go.
Let me know, how it goes.