It’s possible that nothing happened to the sun. I absolutely believe an apparition appeared to the children, but it wasn’t Mary. Mary would have given the glory to Jesus. This apparition focused more on herself/her immaculate heart. (The rosary is focused on Mary as well.)
Anyway, here’s the Wikipedia recap of the sun phenomenon. Before anyone disparages the source, please note that it is copiously footnoted/documented. The original source material is available for anyone to scrutinize and evaluate.
What happened then became known as the “Miracle of the Sun”.
Various claims have been made as to what actually happened during the event. The three children who originally claimed to have seen Our Lady of Fátima reported seeing a panorama of visions during the event, including those of Jesus, Our Lady of Sorrows, Our Lady of Mount Carmel, and ofSaint Joseph blessing the people.[14] Father John De Marchi, an Italian Catholic priest and researcher wrote several books on the subject, which included descriptions by witnesses who believed they had seen a miracle created by Mary, Mother of God.[10]According to accounts, after a period of rain, the dark clouds broke and the sun appeared as an opaque, spinning disc in the sky. It was said to be significantly duller than normal, and to cast multicolored lights across the landscape, the people, and the surrounding clouds. The sun was then reported to have careened towards the earth before zig-zagging back to its normal position.[7]Witnesses reported that their previously wet clothes became “suddenly and completely dry, as well as the wet and muddy ground that had been previously soaked because of the rain that had been falling”.[15]
Not all witnesses reported seeing the sun “dance”. Some people only saw the radiant colors, and others, including some believers, saw nothing at all.[16][17][18][19] The only known picture of the sun taken during the event does not show anything unusual.[20] No unusual phenomenon of the sun was observed by scientists at the time.[6] A number of theologians, scientists, and skeptics have offered alternative explanations that include psychological suggestibility of the witnesses, temporary retinal distortion caused by staring at the intense light of the Sun, and optical effects caused by natural meteorological phenomena.[21]
https://en.m.wikipedia.org/wiki/Our_Lady_of_F%C3%A1tima
I don’t see anyone arguing that something didn’t happen.
What’s being challenged is the opinion over what exactly it was.
The enemy, Satan, can even appear as an angel of light and his workers as ministers of righteousness, so believing every thing that comes down the pike is dangerous.
You are quite correct about who is getting the credit here and that all the glory should go to Jesus. That alone casts doubt about the source.