A level is a designation that any permanent can have. A Class retains its level even if it stops being a Class. Levels are not a copiable characteristic.
July 23, 2021 · Adventures in the Forgotten Realms
The existence and values of these alternative characteristics is part of the object’s copiable values.
October 4, 2019 · Throne of Eldraine
rule 716.2b not present in this release
August 23, 2019 · Commander 2019
Exile every object on the stack, including the object that’s resolving. All objects not on the battlefield or in the command zone that aren’t represented by cards will cease to exist the next time state-based actions are checked (see rule 704, “State-Based Actions”).
July 22, 2016 · Eldritch Moon
rule 716.2b not present in this release
February 1, 2014 · Born of the Gods
Each other player, in turn order starting after the player who suggested the shortcut, may either accept the proposed sequence, or shorten it by naming a place where he or she will make a game choice that’s different than what’s been proposed. (The player doesn’t need to specify at this time what the new choice will be.) This place becomes the new ending point of the proposed sequence.
September 30, 2011 · Innistrad
Each other player, in turn order starting after the player who suggested the shortcut, may either accept the proposed sequence, or shorten it by naming a place where he or she will make a game choice that's different than what's been proposed. (The player doesn't need to specify at this time what the new choice will be.) This place becomes the new ending point of the proposed sequence.