Thin pothos stems reveal what the leaves do not

This is a pothos, and it does not look diseased. Its leaves are green and firm with no obvious damage, but the stems are long, thin and rather sparsely leafed. That is typical of a plant stretching for more light rather than suffering from something more serious.

What will help most now

Give it as much light as possible without harsh, scorching midday sun. At this time of year in Sweden, indoor light quickly becomes less sufficient, so a position that worked earlier may now be too dark. A window with plenty of daylight usually makes the biggest difference.

For a fuller plant, cut back some of the longest stems just above a leaf joint. It will often produce new shoots lower down and look bushier. You can also put the tip cuttings into the same pot.

Water only once the compost has dried out a little way down. Do not give extra water to compensate for thin stems; the issue visible here is light rather than watering. Keep an eye on new leaves too: if they become smaller and the gaps between them lengthen further, the plant needs an even brighter position.