Does Raspberry Pi 2 crashes, freeze or turns off in bright Sun? From what I have read till now a Xenon Flash or Laser Pointer induces glitches causing the board to malfunction. Normally the strong light of the Sun should do the same and possible generate a continuous voltage on that 3.3 V line, not just a short lived sinusoidal signal that quickly attenuates in time.
Many, many years ago, as a young post-graduate I assisted a colleague working with a pulsed-200kV coaxial Xenon flashlamp**. That device had a sub-nano second current rise-time (cf. the >1uS risetimes of typical, photographic flash-guns of the period) and I suspect that this may be "part of the problem". Such flashlamps, IIRC, also have a higher "colour temperature" than the sun (ie. are "bluer").
** O.T. anecdote - one day, when I wasn't there, he tried connecting a 5kV rated capacitor between the "earth end" of the tube and a point ~0.5m away on the metal sheets forming the "ground plane" on the bench top. When he fired up the marx-bank that generated the 200kV pulse said capacitor "exploded into dust" ie. too much voltage developed across it as the pulse (edge) propagated.
Still running Raspbian Jessie or Stretch on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W, 2xP3A+, P3B+, P3B, B+, A+ and a B2) but Buster on the P4B's. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm