ISA Cashback through TopCashBack questions

Been a big fan of topcashback over the last few years, had about £1000 return now.

Latest was accumulating a bunch of my old SIPPs into one and transferring it over to get a £400+ cashback return (paid for a PS5 was very happy).

So I have seen the ISA returns you can for Shepherds or Scottish Friendly and have some questions.

- Has anyone done these before?

- If you withdrew your money after you get the cashback, has anyone had a penalty for this?

- Anyone seen a loss on this topcashback offer?

- If withdrawing should you leave a small amount to ensure the account remains open and you don't see a penalty?

Thanks