Check Hibernate SQL Output
Enable SQL query logging to see what queries Hibernate is executing:
Add this to application.properties:

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true

Check the console logs when making the GET request. If Hibernate is querying player_stats instead of "Player_Stats", it means case sensitivity is the problem.
Ensure Entity Scanning Is Enabled
This ensures Spring Boot recognizes Player as a valid entity.

Try changing to @Service on PlayerService and check

PostgreSQL treats unquoted table names as lowercase by default. Your entity is mapped to "Player_Stats" (with mixed case), but Spring Boot, by default, generates queries using lowercase (player_stats).