My friends and I have always done presents for each others kids at their birthdays, my DCs are 8 and 12, one friend has a DC age 7 and another's are almost 15 year old twins. Last year, my oldest DC didn't receive any birthday presents from these two friends which I thought was odd but of course didn't question it. They both gave gifts to the younger one (his birthday is right before Christmas and we met up to exchange Christmas presents so they dropped off younger one's birthday presents at same time).
About a month before my friend's twins turned 14, I asked on WhatsApp chat if were were still doing birthday presents for each other's kids, to which they said yes. I've since bought gifts for all their kids however, the same thing happened again recently in that they never bought anything for oldest DC when he turned 12. We all usually meet up once a month and that's when gifts tend to be exchanged if there wasn't a party for the child in question, but there was nothing beyond a happy birthday via WhatsApp to DC.
I'm not sure what to do going forward here, part of me thinks 'fuck it', especially as my 12 year old noticed this year. But will I just look like a tight-arsed meanie if I don't bother?