1. Regional restrictions: Double-extraction lemon tea may only be sold in certain regions, so if your region is not within the sales scope, you may not be able to buy this product.
2. Seasonal supply: Double-extraction lemon tea may only be sold in certain seasons, so if you miss the sales season, you may not be able to buy the product.
3. Discontinuation or off-shelf: Double-extraction lemon tea may have been discontinued or off-shelf, so you may not be able to buy the product.
4. Insufficient stock: The stock of double-extraction lemon tea may have been sold out, so you may not be able to buy this product.
If you want to try double-extraction lemon tea, you can try to find the product in the local tea shop or supermarket, or buy it online.