He and his company did do well during the pandemic, and the company's stock did well too, but it was a different economic time. Consumer prices were not being driven up by the actions of the government.
But now as a result of prices being driven up the consumer is buying less, making companies less profitable. Put together with interest rates are going up, making loans for investment cost more and look less appealing, for expanding the business.
So putting those two negative factors together results in the stock market going down, resulting in Amazon as a company being worth less.