Hello!
One of my violets has brown, kind of watery looking spots on this violet (the violet with light green leaves and white decorative spots). I thought it was because of overwatering so I took out the whole plant out of the pot and left it to dry for one day. I also removed all of the leaves which had these brown spots on them. But today I saw these brown spots on the leaves again. Is it actually because of overwatering or some fungus/bacteria? I never watered this plant from the top.






Also, these two african violets (purple flowers) have these dark spots. About half a year ago they looked gorgeous - big, firm, green leaves (look at the photo below). And now they're small, sometimes turn yellow and they have these brown spots (photo below, almost black leaf). They were repotted several months ago to the exactly same type of soil and the same pot (I repotted them because they had been previously repotted around 2,5 years before). I tried increasing the number of fertilizing them (once a week) but nothing changed.

I don't think these problems appeared because there's less sunlight at this time of the year. I have 5 more violets in the other rooms and they have firm and nice leaves as usual.

I would be very thankful if you helped me because I tried so many things to save these violets and they just don't work...

Most likely cause is getting water on the leaves. With the leaves generally horizontal, water on the leaves is not good. The leaves hairy surface holds the water leading to a fungal rot.
The rot is soft and tan/brown just like you describe. It can spread and consume the whole leaf and eventually the plant.

I agree, it looks like the leaves may have gotten wet. This plant generally does not like its leaves wet at all.

If you are watering from the bottom, then it is unlikely that the leaf spot in the photo was caused by water on the leaves. Water on the leaves doesn't explain the other issues.

The symptoms on the variegated AV are consistent with overwatering, which you mentioned. Taking the plant out of the pot to let the soil dry is not an appropriate remedy for overwatering and that may have aggravated the problem. When properly potted, the top half-inch of soil should dry out about a week after a thorough watering.

You wrote that you repotted the other AV's, but used the same pot and soil. Does that mean you removed all or some of the original soil from the rootballs?

Fertilizer is not medicine and is probably aggravating the problem, so I suggest stop using it.

Repotting can create many problems with AV's, especially when done incorrectly. BTW, AV's do not need their soil replaced or replenished even after many years.

In general, AV's do best if left in the same pots and in the same location year after year and with consistent care. Repotting and disturbing the roots disrupts the flowering cycle.