They aren't actually cheating, that smiley face you see to the top left of your items... is called your fun level. Which decides how fast you can get plutonium (it wasn't always this way, but changed a few years ago). It makes it so you can't go into your house and camp at the plutonium or not play the entire round and still get the plutonium easily (it's still possible though!). If you want to maintain a good fun level, just play at the start of the round and don't go into your house.
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Time difference between 100% "fun level" and 0% "fun level" when getting plutonium
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How long for "fun level" to reach 100% & how long for "fun level" to reach 0% (once enter house)
https://youtu.be/HEpZ1AJP56Y