There is something strange happening with crypto subreddits

I happened to be checking subscriber growth for a few subreddits, and noticed something odd.

In the last two weeks, a few select crypto-related subreddits have suddenly seen an absolute explosion in number of subscribers. Specifically, it is four subreddits: /r/bitcoin, /r/ethereum, /r/nft, and for some reason /r/kryptostrassenwetten , a tiny sub in comparison to the rest. Regardless of their size, they have each gained about 600k subs in those two weeks, very steadily over the period. For the last one, that represents an increase of 1000% because of its small initial size. It also makes all four the fastest growing subs on all of reddit over this period, on paper at least.

You can see on this graph below how abnormal the sudden spike is, in comparison to the purple line, which is the unaffected /r/cryptocurrency.

This is clearly bot behavior. But why? Who is doing it, why only target those specific subs, and why hasn't Reddit done anything about it yet? Anyone want to speculate?

https://preview.redd.it/ooh2y2z7287b1.png?916&format=png&auto=webp&s=3a079bcd050d43e52e2ed3ccb80764d9f3865efc

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