Plain meaning
Start with the shortest useful explanation before going deeper.
Reference to mid-to-late 2021 when Solana experienced explosive growth in TVL, NFT launches, developer adoption, and SOL price appreciation. Invoked both nostalgically to recall that period of rapid ecosystem expansion and prospectively when anticipating the next major Solana bull cycle. The phrase echoes 'DeFi Summer' (Ethereum's 2020 growth period).