So I get where you're coming from with it definitely; there have been so many corners cut by big drug manufacturers before this that it's very reasonable. But this one is at least partially different since up till now a lot of the problems have been economic; justifying the research expense, current cost of the disease they're targeting etc. And one of the few things we know about this vaccine is that there is a market for it and funding for the research. Now, the decisions about rushing to market could be bad or could create new harms, but given how many unknown harms there are to having covid in the first place it's going to be a hard thing to qualify whether they're being irresponsible. But I think it's generally good that they're moving as fast as possible on the vaccine.

Also, this might make your fears worse; but they designed at least the modena vaccine in only 2 days after the genome was published, and the entire time since then has been manufacturing it, refining it, and testing it. There are also a wide variety of different types of vaccine being developed.

Here's a thing from Nature about all the different vaccines being studied: https://www.nature.com/articles/d41586-020-01221-y