Most likely an old miner from 2009 — not Satoshi — just moved 50 BTC mined merely one month after the first Bitcoin block was mined.
Source: https://cointelegraph.com/news/bitcoin-price-unfazed-by-50-btc-transaction-from-satoshi-era-wallet
Bitcoin Price Unfazed by 50-BTC Transaction From Satoshi-Era Wallet
May 20, 2020
CoinTelegraph