Arcane season 2 officially introduced the multiverse, providing a glimpse of other timelines and hinting at the show’s true relationship with League of Legends. From the beginning, there’s been intense speculation about the relationship between Arcane and the games on which this tremendous animated show is based; is Arcane a prequel, or is it something more? Most viewers had assumed the question would be resolved in comments from the creators, but instead it’s likely resolved by the simple idea of a multiverse. Arcane is another timeline, meaning anything can happen.

https://screenrant.com/arcane-multiverse-alternate-timelines-explained/