Certainly sounds like canaries telling us the rest of the economy is not doing great. (Not warning us that it's going to have problems. Telling us it already does.)
Happily, this wasn't actually the case. Canaries faint long before they die and miners would carry small resuscitation chambers where the canaries could be reawakened in an oxygen-rich atmosphere. The Science and Industry Museum in Liverpool has one in their collection: https://blog.scienceandindustrymuseum.org.uk/canary-resuscit...
Interesting, but I frankly doubt the birds remained utterly unharmed. Birds are really sensitive to many gases, with the common anecdote being to not cook with nonstick pans if you have a parrot.