@Milk-Destroyer said:

Any coffee drinking plants in the audience, care to elaborate?

Plants appreciate coffee grounds as fertilizer. But what about coffee poured on the soil?
Short answer: No. Undiluted caffeine = herbicide.
It's a trap many people fall into, thinking they're doing the right thing.
While coffee grounds (already brewed and decomposed) are often appreciated in moderation, pouring the rest of your cup of liquid coffee directly onto the soil is generally a bad idea, especially for potted plants. The liquid coffee we drink doesn't have the same properties as the solid residue (the grounds). It presents three major risks to plants:

1. Caffeine is an herbicide
   In nature, the coffee plant produces caffeine* for a very specific reason: to inhibit the growth of other plants around it, thus preventing competition for water and nutrients. It is a natural herbicide. Liquid coffee still contains a high concentration of caffeine, unlike coffee grounds, which have been leached by hot water. Pouring it on the soil can inhibit root development in your plants.
   NB: It's the role* of polyphenols to bring defense. Chlorogenic acids are the primary polyphenols in the coffee plant to be considered.
2. Excessive acidity
   Black coffee is very acidic (its pH is often between 4.5 and 5.0). If you pour it undiluted onto a plant that prefers neutral or alkaline soils (such as thyme, lavender, or geraniums), you will acidify the substrate too drastically, which blocks nutrient absorption…
3. The Additive Trap (Sugar and Milk)
   If your leftover coffee contains sugar or milk, it's a recipe for disaster for a houseplant. The sugar will feed harmful bacteria and attract fungus gnats, while the milk fats will rot, create mold, and clog the soil pores, suffocating the roots.

How to recycle your leftover coffee cleanly?

1. Diluted coffee grounds in compost = hormesis effect.
2. 100 ml of black coffee in one liter of water (10%), but only for plants that prefer acidic soil: hydrangeas, camellias, rhododendrons, or houseplants like ficus, and no more than once a month. Still too concentrated.