Oh hey a surly tangent that I'm qualified for. FWIW I have a master's in clinical research and work managing a couple federal healthcare research projects
The 20th century was like the wild west for research. There was a huge surge in interest but minimal regulation. The Tuskogee syphilis study was probably the most fucked up one in the US, but some of the other biggies were the monster study (1939), project mk-ultra (1953-73; yes it's real, no they didn't invent mind control), and the infamous stanford prison experiments (1971). And none of that even comes close to the fucked-upness of the Nazi human experiments or Japanese Unit 731 during WW2.
Of course, there was also a lot of good, ethical research that revolutionized medicine and broadened the scope of human knowledge. Watson and Crick famously discovered the DNA double helix structure in 1953 (shoutout Rosalind Franklin), and the field of psychology basically went from Freud's horny fever dreams to the respectable field we know today due to the focus on studying the mind during this time.
Importantly, all the terrible stuff led to a ton of regulation and a focus on ethics. The Nuremberg trials led to the establishment of the Nuremberg Code in 1948. It advocated voluntary participation, informed consent, avoiding harm, and ensuring quality. You might be thinking 'no shit,' but it's a big deal. In the US, congress responded to the Tuskogee syphilis study by passing the National Research Act of 1974, which would result in the Belmont Report (1979) that still guides research ethics today. You'll notice all the stuff above happened before that point. None of it would be approved today. Hell, it takes a month for my review board to approve an eight word change to our protocol. Modern research in the US is well regulated and very conscious of its ethical concerns. It's also an important part of our power on the global stage, but that's a different conversation.
Bonus fun fact: when a researcher is awarded a grant, they don't make any money from it.