Over 50, got both Moderna shots (second was April 26th). My experience was:
1st shot, severe arm/neck pain for about three days afterward, no fever/chills/etc.
2nd shot, about 4 hours afterward started to get fever and got very tired. Slept from around 7 pm on the 26th until 5 am on the 27th. Totally missed an entire day! After I woke up I was totally fine except for a small amount of pain around the injection site.
OTOH, my husband got both his at the same time and he had almost the same pain as I did with first shot but nothing, not even at the injection site, with the 2nd.
It might be worth noting that I am a tiny (5'1, 103lbs) female and he's 6', 250lbs. Maybe the smaller you are the more it knocks you out?