I’ll answer that with an anecdote. Some time ago I posted about some wonderful gourmet meat pies made by a small bakery that my nearby supermarket was carrying. Then they stopped carrying them, and since others sources and the bakery itself were somewhat far away, I hoarded them in my freezer for an overly long time. I searched for the post in question and it was made in March, 2024, and I would guess that it was probably more than a year later before I got around to having one of those pies. It was well past its frozen best-by date.
There is no horrific tale to tell here. The pie didn’t kill me or make me sick, but it definitely tasted off. It had lost all its original appeal. And it was tightly wrapped in heavy plastic inside the box, so the problem wasn’t freezer burn.
I suspect the same will happen with your ancient frozen shrimp. It isn’t unsafe, but is likely to have an off-putting taste or texture. The worst effect may be that it will make you dislike shrimp afterwards, which would be unfortunate!
Last year I took a pound of ground beef that I thought had been well-sealed and let it defrost in the refrigerator. When I went to cook it, however, it definitely smelled off. I had to rethink my dinner plans.
The shrimp is in the store packaging, so I’m not sure if it will show any signs of freezer burn.
I would certainly smell it between opening/defrosting it and actually cooking it.
fwiw, I’ve given up freezing ground beef, because I don’t think it keeps well, I think it tastes “off” pretty quickly. (It might be relevant that I like my burgers plain. And that I tried making turkey keema once, and hated it because it tasted like bland turkey and not like rich beef.)
I have a freezer full of steaks, although I’ve stopped that subscription. I certainly hope so!
(I’m also expecting a shipment of a few racks of lamb, some ox tails, and some short ribs soon. That’s from another company that let’s me order what I want when I feel like it, instead of shipping me a regular order.)
I’m usually not much of a ‘salad as a meal’ person, but years ago I used to occasionally go to a restaurant for lunch that had a fantastic shrimp salad. It was good enough that I sometimes made it at home.
I don’t remember the exact ingredients, but it was similar to a Caesar salad— with crisp romaine lettuce, shaved Parmesan, quartered artichoke hearts, croutons, probably some diced red onion, and of course cold cooked shrimp, topped with, I think, Italian dressing. Would work with Caesar dressing too, for sure. I don’t think the restaurant version had it, but sliced up avocado would be a great addition as well. Makes for a nice refreshing Summer lunch.