It's not really out of the blue. She announced at the start of the week that she'll be doing a special week of collabs, where the person she's collabing with thinks of what they'll do together:
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Pekora has been pushing hard for special streams this year like Hardcore Minecraft, ARK, the members-only Minecraft server, SIlent Mario Party, etc. I don't think there's a real reason to be concerned about graduating, just seems like she's been pretty motivated ever since doing her solo live back in December.