The size of the sample compared to the size of the population doesn’t really matter. What matters is how representative the sample is.
If they got a truly random sample (they didn’t), then 1000 is plenty.
Realistically, it’s probably 1000 Millennial and Gen Z Credit Karma users (already a niche group) who bothered to open an email and take a survey, which is not a realistic representation.
The whole thing is batshit insane, but possibly the most insane claim is that Lyme disease came from vaccine research.
There is strong evidence that Lyme disease has been around for hundreds, if not thousands of years. There's evidence of Lyme disease in Ötzi's remains.