How to grow a Portulacaria afra 'Medio-picta' bonsai? Solve the frequent leaf drop that ruins its looks

Portulacaria afra 'Medio-picta' - the moment I heard this name I found it very novel and very upscale, so what exactly is it? Actually, it is a variegated cultivar of the elephant bush (Portulacaria afra), and it has properties similar to the elephant bush. The leaves of the elephant bush are entirely green, while the leaves of Portulacaria afra 'Medio-picta' are green in the middle with edges mixed with white and other colors, which is very beautiful.
Many people who love growing plants will have a pot of Portulacaria afra 'Medio-picta', but growing it comes with a lot of trouble, for example the plant keeps dropping leaves. The ornamental value of Portulacaria afra 'Medio-picta' lies entirely in the beauty created by the different colors of its leaves; if the leaves all drop off, what ornamental value is left?
Sunlight
Portulacaria afra 'Medio-picta' is a plant that loves sunlight very much, and it needs conditions with plenty of light. Normally we can place it in a spot indoors with plenty of light. But in summer, we should shade it appropriately and give it just one to two hours of sunlight a day. This is because in summer Portulacaria afra 'Medio-picta' grows very slowly, and only sufficient light can ensure its leaves are thick and compact, and its variegation is very vivid.
If the light is not sufficient enough, then its branches and stem nodes will stretch out, the leaves will become dull and lusterless, and a state of malnutrition will appear; over time, it will also cause leaf drop. Furthermore, if the light period in summer is too long, it will slow the plant's growth and consume the nutrients inside the plant, which is not good for the plant's growth.
Watering
We all know there are many finer points to watering plants, so here we need to pay very close attention. Generally, we only need to water the surface soil thoroughly. Remember never to water too much; too much easily makes the roots rot, so just the right amount is fine. Also, we should not water in the evening; we should water in the morning.
Ventilation
As for the issue of ventilation, surely everyone pays very little attention to it. This is an issue that cannot be ignored; once we fail to notice it, it can easily cause the plant's death. And Portulacaria afra 'Medio-picta' very much needs a place with good ventilation; generally we place it at the edge of a balcony where ventilation is good. If ventilation is poor, over time it will cause the leaves to fall off, and we still cannot find the reason for the drop.
Fertilizing
At this point we can consider using a fertilizer mainly of nitrogen and potassium. Nitrogen fertilizer can promote thick leaves and faster growth; potassium fertilizer can promote thick, strong branches and a sturdy root system. And since Portulacaria afra 'Medio-picta' grows slowly, we can use a slow-release fertilizer, and the nutrient strength of slow-release fertilizer happens to meet its growth needs. Moreover, it will not burn the seedlings because the nutrient strength is too high, and it can still ensure the plant's growth.
I hope these little tips can be of some help to you.