Yes, I lost quite a few from Live Aquaria the last time I ordered, probably 40% so I decided not to order anymore from their CA facility.
However, I have ordered seahorses from both Hawaii, (Ocean Rider) and Florida (Seahorse Source) and never lost a single one and I have ordered fish from KP Aquatics and never lost any.
Back before the pandemic when you could actually count on delivery companies to honor their delivery schedules, I lost maybe 5%. They were mostly due to poor specimens being shipped.
Since the pandemic and shipping is all messed up, I've stopped ordering any livestock online. Missing boxes, shipments lost in the hub, packages that originated in my home state to only be sent 5 states down, then back to my state, etc, etc.
I haven't ordered fish shipped to me in quite a while but I don't remember ever have a doa. Nems on the other hand I will no longer have shipped to me. Tried twice and both times they were doa. I have a good saltwater only lfs that I use. I let the owner now what I want and if he can sourse them I go to the store and get them when they arrive and still bagged. I figure its less stress on the fish and the owner gives me good prices because it removes the risk of the fish dying while under his care.