Solved is a designation a permanent can have. It has no rules meaning other than to act as a marker that spells and abilities can identify. Once a permanent becomes solved, it stays solved until it leaves the battlefield. The solved designation is neither an ability nor part of the permanent’s copiable values.
April 14, 2023 · March of the Machine
rule 719.3b not present in this release
November 18, 2022 · The Brothers’ War
Both a prototyped spell and the permanent it becomes have only its alternative set of power, toughness, and mana cost characteristics. If that mana cost includes one or more colored mana symbols, the spell and the permanent it becomes are also that color or colors (see rule 105.2).