Hihi any idea what could have caused a 6mo on fm to puke (Merlion) after milk feed while burping?

Have you started weaning. There's a likelihood that baby could be having indigestion or baby drinks too fast. Also by 6 months baby should be able to burp on their own, there's no need to help baby to burp. If baby cries too much before bottling, baby will also vomit milk out due to the amount of air swallowed and then coming out. As they are capable of burping on their own, additional help may cause the expulsion of air to be even stronger. Keep baby slightly elevated when bottling and only put baby down after 15 mins. Ensure FM is not too cold. Always check temperature before giving and let baby drink slowly. If baby is gulping down milk, the milk flow maybe too fast for baby and you want to consider giving the smaller teat till baby is ready to accept a bigger sized teat.