What are the vaccination proof requirements for transiting through Singapore to Thailand?

When transiting through Singapore to Thailand, travelers need to provide vaccination proof which is primarily required for flights part of the Vaccinated Travel Lane (VTL). For Singapore, proof of vaccination including a digital QR code is necessary if flying under the VTL program. Notably, the timing for the RT-PCR test is different; it has to be taken 48 hours prior for Singapore as opposed to 72 hours for Thailand. A user mentioned that during their transit in late October, there were no checks on vaccination proof in Singapore, but they had to fulfill requirements only at their point of departure.