A comparison image of ETH's price behavior before and after major upgrades. Overall, ETH's price tends to rise sharply before the upgrade.
The Merge (15/9/2022)
1–4 weeks after the upgrade: A light distribution pattern appears, trading volume decreases, price breaks down from the short-term support zone → a slight sell-off occurs (about -20%) but not a panic sell. The 'sell the news' effect, combined with short-term holders taking profits after the hype phase.