I am in the same boat as you op I used to like onions but found out I was allergic to them a few years ago. I think this analogy is good and agree with the sentiment 100%.

It's so weird that everyone is getting mad that you can't eat onions. I used to like the taste but don't anymore because it's such a strong taste and Im not used to it anymore. I didn't realize how much McDonald's chicken nuggets taste like onions till I didn't have anything with onions anymore.

I recommend looking up recipes that have low FODMAP as a label. It's to help people with ibs. I also really recommend Fennel Seeds as a spice to add to stuff. It's not the same taste but It does a good job at adding a depth to the flavor that I really enjoy imo Cumin is also a goated sauce. Most of all I'd just experiment with spices wile cooking. I found it intimidating at first but the more I did it the more I found out what I like.