I have the issue where sims take a serving of every group meal (incl cake) and put it in their inventory instead of eating. I do however not have any issues with birthdays/weddings as others are reporting, as I can consistently avoid it, by only baking the cakes when already full (my chefs are always inspired when cooking, just in case that would matter).
I normally play modded (MC), but I did an unmodded test and was able to reproduce the issue only if the chef is hungry (yellow or lower) when cooking.
I did have another new issue with the wedding cakes though. Bringing a cake with topper to the venue makes it unusable (groom and bride both refuse to cut it - says they must wait for the newlyweds). One couple got around the issue by baking a new cake at the venue and were able to cut that one. Another couple couldn't even cut a new cake baked at the venue, but could cut the original cake when loading the save before travelling to venue and throwing the wedding at home instead(so the same cake worked before traveling, but not after).
Windows 10, Base game + OR, GTW, LP, PP, SP, CK, GT, DO, CL and VG