Every distinct wording since 2010, newest first.
February 18, 2022 · Kamigawa: Neon Dynasty
“[Cost]: Level N — [Abilities]” means “[Cost]: This Class’s level becomes N. Activate only if this Class is level N-1 and only as a sorcery” and “As long as this Class is level N or greater, it has [abilities].”
July 23, 2021 · Adventures in the Forgotten Realms
“[Cost]: Level N — [Abilities]” means “[Cost]: This Class’s level becomes N. Activate this ability only if this Class is level N-1 and only as a sorcery” and “As long as this Class is level N or greater, it has [abilities].”