https://kusama.subsquare.io/referenda/511

Referenda is a proposal to increase the parachain validator set size from 600 to 700. This will make the total number of usable cores increase to 140. The maximum backing group size will stay at 5. The setNDelayTranches will be updated from 257 to 299 to keep the number of assignments per candidate around 2.33. This value is important and can be found in a research paper and a GitHub issue.