This is normal as the sphincter is still immature and is called gaate oesophageal reflux . Babies usually outgrow this. Until baby is active, gaining weight, feeding well despite spit ups, not irritable, spit ups are not yellowish greenish in colour , abdomen is soft, no abnormal postures you need not worry. Feed in small quantities frequently, positioning and latching should be proper.keep the baby upright and burp after feeds for about 20-30 min.

Greetings It is common for late preterm babies to spit up curdled, creamy milk because their digestive systems are still maturing. This frequent spitting up through both the nose and mouth often resembles gastroesophageal reflux, a temporary food intolerance, or simple overfeeding as they transition formula stages. Keeping the infants upright for 30 minutes after feeding and offering smaller, more frequent portions can significantly reduce this backflow.

It is quite normal. There are multiple reasons as gastric reflux, overfeed, aerophagia etc. Just monitor for proper weight gain. All you need to do is proper burping/tummy time.

Burp properly

Do proper burping

Spitting up curdled milk from the mouth and nose is common in premature babies, since the valve between the stomach and feeding tube is still immature at 34 weeks. The milk looks curdled because it is partly digested, and some comes up through the nose simply because the mouth and nose are connected inside. This usually settles on its own as your babies mature over the coming weeks.