It’s not nail polish or decoration — it’s a marking method using colored wax (usually red) that is commonly used in agriculture and supermarket supply chains, with the following purposes:

✅ 1. To prevent bananas from ripening too quickly

The top stem of the banana (where it’s most exposed to ethylene gas — the gas that triggers ripening) is dipped in red wax or coated with a special substance to slow down the ripening process.
This is a widely used technique to extend shelf life during transport and display.

✅ 2. To identify batches or origin

Each wax color can represent the delivery date, supplier, or the treatment applied (e.g., organic, chemical-free, etc.).
This helps supermarkets manage inventory and expiry dates more efficiently.

✅ 3. To prevent customers from breaking off individual bananas

Some supermarkets prefer that customers buy the whole bunch instead of picking individual bananas.
Applying wax to the tips makes it harder to separate them, helping keep the bunch intact.

⚠️ Is it toxic? Is it edible?

No, it’s not toxic. The red layer is usually food-grade wax, which is safe and doesn’t affect the edible part of the banana.
However, it’s still a good idea to wash your hands after handling the bananas to avoid transferring the wax to your mouth or other food.

In summary:

The “red-tipped” bananas in the photo are a result of preservation and labeling techniques — not nail polish or decoration tricks.
This practice is quite common in large supermarkets across Europe, such as in Germany, the Netherlands, or Switzerland.