What comes to my mind at first as a possible treatment is better soil irrigation and the use of antifungal agents.

If the leaves get crinkly and the tips and edges turn brown first, it could be a nutrient deficiency or salts in the soil or water. As are citrus and avocados, mangoes are sensitive to too much boron or too little manganese, zinc and iron. https://www.latimes.com/archives/la-xpm-1997-06-22-re-5771-story.html?_amp=true

Either the plant is not getting enough water or else salt has accumulated in the soil. Both can occur at the same time, but either one can result in mango leaves with burnt tips. ... Usually, sporadic irrigation or extreme fluctuations in soil moisture is the kind of cultural care that results in tipburn. https://www.gardeningknowhow.com/edible/fruits/mango/what-causes-mango-tipburn.htm

Check https://plantvillage.psu.edu/topics/mango/infos/diseases_and_pests_description_uses_propagation

The symptoms are started on upper young leaves of 7 trees on one variety.There is no symptoms on the lower older leaves. Do you think that it will be potassium or magnesium deficiency?

Mangoes are well adapted to many types of soils, and can produce fruit in sand, loam or clay soil. Regardless of the soil type, the most important growing condition is good drainage. Trees grown in soils that retain moisture are prone to disease and poor fruit quality. A soil pH of 5.5 to 7.5 is preferred; trees have a harder time in alkaline soil. Fresh potting soil meets these requirements, which is typically what container-grown trees are planted in. However, after several years of growth, it becomes necessary to check soil conditions and amend when needed.

High soil salinity typically leads to the yellowish-brown spots that appear at the tip of mango (Mangifera indica) leaves, known as leaf burn. Mango trees are sensitive to high salinity, which occurs for numerous reasons. In addition to high salinity, mango plant leaves turning brown may also come from insects and diseases.

The bright colors of mango skins are largely determined by what nutrients are most prevalent in the soil. Soils high in potassium result in red peels, while high-nitrogen causes the skin to stay green. Generally, high nitrogen fertilizers should be avoided. Fertilizers should contain equal parts of nitrogen, phosphorous, and potassium, for example an N-P-K ratio of 6-6-6. When the trees begin to bear fruit, slight increase in phosphorous and potassium fertilizers would benefit fruiting. Often times, fertilizer for tomato plants is suitable to mango trees. Look for fertilizers with micro-nutrients magnesium, zinc, manganese, and iron to further optimize mango production.

Nutrient deficiencies are to blame for two common mango tree problems. Weak fruit production, referred to as "mango decline," is often attributed to manganese and iron deficiencies in the soil. In addition to poor fruit production, this condition can be identified by stunted and dying leaves or the simultaneous arrival of fungal problems. Mango decline can usually be improved with manganese and iron soil amendments. An internal breakdown of the fruit itself, termed "jelly seed," causes fruits to become mushy around the seed. This condition is aggravated by excess nitrogen in the soil and can be mostly alleviated by reducing nitrogen and increasing calcium supplements.