If you fund IB through fintech, be prepared within 6 months or so to receive email from them requiring proof that transfer is from you, otherwise account shut down.

Can, it will reach. Make sure to keep all documentation as you will be queried by IB for investigation into source of funds.

The reason is simple - they expect that your money comes from account with your name. Which is the case for SGD moved from CIMB/MBB or whatever SG account.

When you use fintech, they see that money is coming to your name from an account with someone else's name. Straight red flag.

Yes. But not sure is it once only or throughout the whole duration you used it.

Eg. You used fintech to move money into Ibkr for say 7 months. Do they want all 7 months documents or just the recent one only?

No issue with using sg banks.

Their SGD to USD rate is really quite good. If you're transferring 3 digit ringgit at a time maybe it will be painful the amount of fees, but above that the fees is 1.50 USD I think, so you don't actually lose out very much. How much is your time worth (and the worry) when they bother you for verification?

Is CNDX what you are looking for? Better double check to be sure.
https://www.ishares.com/uk/individual/en/pr...q-100-ucits-etf

It's listed on LSE, domiciled in Ireland (is a UCITS), traded in USD, is an accumulating ETF (dividend auto reinvested at a fund level). ER is 0.33% so its slightly better than CNX1.