Max RM30k. Anything more will earn you less than 4%p.a. If you want to be safe, rm29k. That way you know you are always getting 4%p.a even with the interest every month.

while waiting for responses, perhaps you can try this for some added info while you wait for response

Above rm30k also almost 4% already maa...

Remember it is not fixed 3.9% 🤦‍♀️ the reason why Feb is high it is because it is only 28 days hence interest would be higher compared to March onwards