https://wccftech.com/super-smash-bros-ultimate-update-8-0/

Super Smash Bros Ultimate update 8.0.0 will be arriving on Nintendo Switch within one week from now, Nintendo has announced.

Exact details of the major update are unknown, but Nintendo did share that the update will pack fighter adjustments. As such, players will be unable to view replays saved prior to version 8.0. Players who want to retain their replays will need to convert them to video in-game via Vault → Replays → Replay Data → Convert to Video.