Free the end

Put the summary of the bug you're having here

What I expected to happen was...:
 I killed ender dragon and i didnt get achievment free the end.

What actually happened was...:
 I killed him in in survival 1.15.2 and didnt get achievment free the end iam.

Steps to Reproduce:
1. Go in nether
2. Kill ender dragon
3. maybe i didnt get achievment