The org.springframework.boot.autoconfigure.EnableAutoConfiguration key is gone as of boot 3.
There is validation for this key found in spring.factories file. However, it only follows its default setting AUTO. In other words it is flagged if found in a Boot 3 project. There are also settings ON and OFF:
ON would flag it in any boot project not just 3.x
OFF would not show this error.
It appears ON and OFF support is missing.