Have I Killed My Elephant Snails?

I’ve had two adult elephant / rabbit snails living in my tank for about two years. Recently added more fish, realised I was in mini cycle and bought Prime to help between water changes.  Then decided to add more plants, and the man in the shop recommended Flourish. He was aware I kept snails.
In the last two weeks both elephant snails have died. The nerite is fine, and so are multiple mts. I’m hoping the baby elephants are fine and hiding somewhere, but worried they are not.
I now read flourish contains copper... did I kill my lovely snails??!!
Thanks for any help / advice.
Ps I also have two Armani shrimp and the fish are ember tetra. It’s an aquanano 40. Approx 55l aquarium.

Thanks Sue, Yes that’s the one, it’s a seachem product but says exactly that on the bottle. I dosed as per instructions,  not particularly carefully, not really thinking about how the small volumes involved in a small tank may make it easy to overdose, also not thinking it would have Cu in it.
Ive recently seen one of the baby rabbit snails so am happier now! Hopefully it was just an unhappy coincidence that they both died within a week or so of each other!
I’m going to dose much less from now on. Does half sound reasonable, or less? What are you dosing?

Ah, yes, that is a lot lower than the suggested dose! I also go for low tech plants, there seem to be plenty to chose from. Initially I used no frets at all, as I started the tank with some garden soil under the sand. But my plants haven’t been doing too well more recently and I was recommended this product. Tbh I think the main benefit to the plants will be me buying another timer for the tank lights - I got rid on the advice of the fire service. Still in two minds about it! But anyway, this is way off topic now!

I didn’t say that very clearly, sorry... got the timer, am still in two minds over whether or not it’ll burn my house down! Lol!

Moderator Matt edit: changed typo as per your message