End gateways don't generate after dragon fight on realms

Put the summary of the bug you're having here

What I expected to happen was...:
I was expecting that defeating the dragon would generate new end gateways.

What actually happened was...:
Both in 1.19 and in 1.20 killing the dragon generated zero gateways.

Steps to Reproduce:
1. Spawn the ender dragon and defeat it.
2. After first successful generation of a gateway, try again to do the ender dragon fight.
3. ...