And now more than half of 5* raids are for shiny Pokemon. Because this is extremely curious, I did a little digging to find out why.

tl;dr: folks widened the previous RNG flaw into a tool that discovers a hidden number exclusive to their games, then tells them where to set their system date forward in time to find their desired shiny Pokemon. So you just run the tool to crunch some numbers, update the system date, and et voila, desired shiny Pokemon that you can share with the world as many times as you like.

How this works:

1. Each copy of Sword and Shield generates a single secret number that it uses to randomize every Pokemon raid den in the game. This number is used along with the system date to determine the Pokemon for that den for that day.

2. About a month ago, Redditors discovered that this logic was flawed. You could lock in the stats and shiny status of any raid den, independent of the Pokemon in it, by updating the system date and experimenting. Then you could roll a separate predetermined list of Pokemon forward to get the 'mon you wanted. (This happens because only some of these properties are preseeded using the hidden number from 1.)

3. A Japanese player of the game realized that you could also crack the hidden number using enough sampling, since the algorithm the game uses is known and isn't especially secure. So they wrote a tool where you catch a few Pokemon within different windows of time, plug in all of their stats to figure out their numbers, then work backwards to the number the game uses for this generation. This works because enough of the variables about raid dens are fixed.

4. Since the game does not save after a raid den is completed, the game can be reset and repeated infinitely, hosting for other players to join in on.

Result: lots of people using the tool instead of spending multiple real-world days grinding for their desired shinies. And unlike save hacking, these are all generated by the game legitimately using its own mechanics against itself.

Worse: while you can ban the _host_ of these raids, any shinies generated on client machines will be difficult to track down since their properties will all be legitimate and their system dates correct. So this is pretty difficult to defend against.

So I think this means that, for the foreseeable future, shiny Pokemon will be common in the current generation of games and its raids, unless GameFreak takes clever action and/or removes shinies from the raid hosting pool entirely. Until then, it's probably worth stocking up.

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Sourcing:
* https://www.reddit.com/r/Shinyraids/
* https://www.youtube.com/watch?v=ikF56AHceJ4
* https://www.youtube.com/watch?v=Atpa8DMbAfM