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Why could tidal locking and stellar radiation make Proxima Centauri b difficult for life to support?

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Habitable zone The habitable zones (green) for stars that are like the Sun (middle), hotter than the Sun (top), and cooler than the Sun (bottom). The red areas are those in which liquid surface water would be lost as a result of a runaway greenhouse effect, and the blue areas are those in which liquid surface water would be completely frozen.

Proxima Centauri b faces significant challenges to supporting life due to its proximity to its host star, a red dwarf, which necessitates an orbit close enough to be within the habitable zone.12

Tidal Locking: Because the planet orbits so close to its star, it is likely tidally locked, meaning the same hemisphere perpetually faces the star. This eliminates a traditional day-night cycle. Without a sufficiently massive atmosphere to redistribute heat, the atmosphere on the dark, cold side could freeze onto the surface, potentially rendering the planet inhospitable.12
Stellar Radiation: Proxima Centauri is a flare star prone to frequent, intense solar flares. These events release massive amounts of radiation, such as the record-breaking ultraviolet flare observed in 2019. Scientists theorize that this intense radiation, combined with the planet's close proximity to the star, makes it unlikely that Proxima Centauri b can maintain an atmosphere, which is a critical requirement for supporting life.2