Chandrayaan 3 landed at around 69 degrees south latitude which isn't far enough south to access the permanently shadowed craters where large ice deposits might occur (and the Pragyan rover uses solar panels for power).

I haven't read specific reasons for choosing that site, but we have never landed that far south, and it will be interesting to see what differences (if any) there are from the more central latitudes, which is a good enough reason on its own.

It may be due to communications problems if a lander came down in one of those shadowed craters. We would not be able to communicate with it. it would probably require relay satellites around the moon to mediate that communication.

I believe Chandrayaan 1 has detected water, but not sure if it was the first one to do so

The definitive discovery of Moon water came from Chandrayaan-1 which carried with it a NASA-provided science instrument called the Moon Mineralogical Mapper—M3 for short—that observed how the surface absorbed infrared light. Using this data, M3 determined that previously suspected water molecules were ice inside the Moon’s polar craters [0].

However, the first direct evidence of water vapor near the Moon was obtained by the Apollo 14 in 1971 [0]. A series of bursts of water vapor ions were observed by the instrument mass spectrometer at the lunar surface near the Apollo 14 landing site.

[0]: https://www.planetary.org/articles/water-on-the-moon-guide

[1]: https://en.m.wikipedia.org/wiki/Lunar_water

NASA LCROSS confirmed it before the Indian mission (which NASA instruments also on the Indian mission confirmed first). After NASA confirmed, Indian officials came out with their own announcement