I beat the End Dragon twice today (the first was the first time on this world) and no city gateway portals have spawned at all. At first, I thought it may have been a one-time glitch, hence the second attempt at killing the dragon.
Linked issues
Comments

Thank you for your report!
We're tracking this issue in MC-184482, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – ✍️ Feedback and Suggestions – 📖 Game Wiki
Duplicate of MC-184482