"Safe" for a payment processor comes down to how card data is handled. With Paystack, the customer enters their card details into Paystack's own secure checkout, not the merchant's systems. The merchant never sees or stores the raw card number, which removes a large category of risk from the business accepting payment.
Paystack holds PCI-DSS compliance — the payment-card industry's security standard — and encrypts sensitive data in transit. Being owned by Stripe and regulated in its operating markets adds further oversight.
KAZI uses Paystack to process payments on invoices and escrow. It is important to be precise about this: the payment-security certifications belong to Paystack as the processor, not to KAZI. KAZI relies on that infrastructure so it never has to handle raw card data itself.