Your DemoApplication class is in the com.ag.digital.demo.boot package and your LoginBean class is in the com.ag.digital.demo.bean package. By default components (classes annotated with @Component) are found if they are in the same package or a sub-package of your main application class DemoApplication. This means that LoginBean isn’t being found so dependency injection fails.
There are a couple of ways to solve your problem:
Move LoginBean into com.ag.digital.demo.boot or a sub-package.
Configure the packages that are scanned for components using the scanBasePackages attribute of @SpringBootApplication that should be on DemoApplication.
A few of other things that aren’t causing a problem, but are not quite right with the code you’ve posted:
@Service is a specialisation of @Component so you don’t need both on LoginBean
Similarly, @RestController is a specialisation of @Component so you don’t need both on DemoRestController
DemoRestController is an unusual place for @EnableAutoConfiguration. That annotation is typically found on your main application class (DemoApplication) either directly or via @SpringBootApplication which is a combination of @ComponentScan, @Configuration, and @EnableAutoConfiguration.
To me it happened in DogController that autowired DogService that autowired DogRepository. Dog class used to have field name but I changed it to coolName, but didn’t change methods in DogRepository: Dog findDogByName(String name). I change that method to Dog findDogByCoolName(String name) and now it works.