I think Liverpool are in a transition period and they've actually been pretty good so far. After being left by Firmino who joined the Saudi league team, Darwin Nunez will now become the successor of the number 9 jersey at Liverpool and during this pre-season match he has proved enough of his contribution by scoring 3 goals in two pre-season matches. With this, we can see that Darwin Nunez is getting more productive and it is hoped that he will also bring this result later when the EPL competition starts. I think Liverpool still have good squad depth for that position and as back-up are Diogo Jota and Luis Diaz who are currently recovering from injury.
I think you are too quick to jump to conclusions because as far as I can remember Nunez also did it last season when he first joined and had pre-season games in fact he scored 3 goals in one match, but after a real season his performance continued to decline and Klopp defended him then said he needed more adaptation. We know Nunez has great potential but besides adaptation he also needs the right partner, this season Liverpool have brought in Dominik Szoboszlai this is Liverpool's attempt to prepare the right partner for him and we have to wait for the official match once the season is running.