Arcane S2 is around 7-8 while season 1 was definitely 10.
Arcane S2 skips over lot of things that was build up in S1 like political situation of Piltover and Zaun, relation btw Jayce-Victor, jayce- cait, Jayce-Mel, Well most of the relation BTW Jayce, Victor, Mel, Vi, and jinx.
And the main focus of the S1 was relation btw jinx and Vi, which was ruined by S2. The one of the major message of arcane was to give others time to heal. To step back and gave person time to forgive themself. Jinx and Vi were obsessed with each other which caused major conflicts in the show. The guilt of jinx pushed her to insanity while Vi herself did not realised that she was pushing Jinx by reminding of her past. This caused jinx to take risk beyond her capabilities. This was depicted in S1 beautifully ,but in S2 Ekko ruined the inner writing.
Ekko is way perfect to be included in arcane. He does everything perfectly. Believe me, for 2-3 days I was thinking why I felt disappointed and upset on S2. This reddit thread help me. If you r fan of Arcane then you should also read this. And if you want to write more depth in your stories then also you should watch arcane then read this thread.
I can't put the words more perfectly the this user :-
https://www.reddit.com/r/arcane/comments/1hceime/s2_spoilers_my_problem_with_ekko_very_long_post/