Hey /u/Insaniaksin! Like another user has said below, you can add `?set_lang=0` at the end of the link to reset it back to english, or click the bottom right flag icon.
As to why it happened, I'm not sure, but here's a possibility: did you maybe click on any RuneScape link at some point, and didn't realise that this link contained a language swap? Example, clicking this link
https://www.runescape.com/game-guide/beginners-guide?set_lang=2
would set your l...
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