I also wonder, since it seems likely for users to sweep all their output chips into a wallet wouldn't this also be obvious?
In addition to ChipMixer's response above,
not doing this is better for your privacy.
If I deposit 100 mBTC and then immediately withdraw exactly 100 mBTC, then that is poor for my privacy.
If I deposit 100 mBTC, and withdraw 4 mBTC today, and then 32 mBTC tomorrow, 16 mBTC next week, 20 mBTC the week after, then deposit another 50 mBTC and combine it with my remaining 28 mBTC... and so on, it becomes far more difficult, if not impossible, to link any of those transactions.
If you are concerned about exchanges frowning upon mixed coins, then you either need to bounce those coins around yourself after withdrawing from ChipMixer, or stop using exchanges with such invasive policies.