SNEK! SNEEECK! SNEK!
there are two types of rattlesnake venom, or there used to be. The Pacific rattle had a relatively mild hemo toxic venom, while the less common Mojave green rattle injected a powerful neurotoxic venom
however there are indications that the two populations interbred and hybrids are commonly found that resemble the common Pacific rattler but having much stronger venom that is both hemolytic and neurotoxic.
Or it's possible the presence of the 3'd venom variant rattlesnake population just went unnoticed until recently.
https://en.wikipedia.org/wiki/Crotalus_scutulatus
The effects of hybridization on divergent venom types
https://www.unco.edu/nhs/biology/about-us/mackessy-stephen/documents/2016-Toxicon-Scutulatus-helleri-hybrid-venoms.pdf
https://www.sandiegouniontribune.com/sdut-1n20rattlers223712-rattlers-reputation-takes-toxic-2009apr20-htmlstory.html