Hello, Yes, no problem...

The button only lights up when you tip the jug. In other words, while you are pouring out water. Then it should briefly light up green or orange or whatever it is when a replacement is required

The time it takes to obtain 1.5 litres of filtered water depends on the filter speed, which is not explicitly stated. In general, the filtration process for water filters takes a few minutes, depending on the filter technology and the amount of water. The BRITA MAXTRA PRO filter cards are designed for efficient filtration, but the exact time may vary depending on the water pressure and filter condition.

The indication of a volume of 2.5 litres is consistent with the type of product often used in Brita glass filter jugs. The glass Model ONE Maxtra Pro also has a volume of 2.5 litres, which suggests that it could be a similar product. However, the exact name "Glass Model ONE Maxtra Pro" does not directly refer to the general description of a 2.5 litre Brita glass filter jug. If you need specific information about this product, I recommend consulting Brita's official product description.

Unfortunately buy a new one.

I haven't tried it yet, but I recommend that you simply wash it off with a soft sponge and washing-up liquid

If you press and hold the light, it lights up green again!

Strange, but in general it is recommended to change the filter every four weeks, even if it flashes green. When you tip the jug, does it flash green? If not, maybe the sensor is not activated. You activate it by pressing on it for a long time.

No, it's made of plastic. Brita states that they use recycled plastic.