Around 7yrs of exp & worked on diff areas like bcknd, frntnd, DB, devops, support, etc and with diff techs. what to learn to make a switch?

Java, springboot, backend is what i started my career with.

currently in support, working mostly on client's warehouse management systems, rectifying data issues, lil bit of Java, SQL, Azure, and system design. my Java is very week, over the years I've tried to strengthen it, learn Data structures, do leet code but no consistency. I'm jack of all, not able to become Ace of one.