TL;DR if you're a software engineer looking for a transparent company and one where you can learn and grow with hard working coworkers, Credit Karma is NOT for you.
1. Cringey + opaque company culture. You get a sense that this is a company that does not value transparency and this is evident from a high, managerial/leadership level all the way down to a everyday interaction level. Abundant use of private DMs + channels on Slack, private calendars, etc etc. If you need assistance with something, instead of answering your question in public for posterity, you will receive a DM. Meetings feel ever so exclusive (not that they're consequential in the first place). The openness and fun captured in the countless company pictures mask the very obvious internal isolation and opaqueness.
2. Extreme and unnecessary bureaucracy. Want to be able to record a meeting? File a ticket for that. Want to download/install software to do your job? File a ticket for that. Want to provision some storage/resource to start your project? File a ticket for that too. So if everyone has to record a meeting, guess what everyone will have to file a ticket. Basically, you have to beg a million other people to get things done around here, and it just basically gives them the ability to say: "Wow, look at how busy I am today; I closed 10 tickets.", despite the ticket just literally being clicking a button or two...
3. Lack of engineering talent and foundation. This is where I may be a bit biased, since I come from a company where my coworkers were all go-getters, willing to put in the extra work and treat their work as more than a job. At Credit Karma, it just seems most people are perfectly content with working from 9-5 (i.e. complacency), doing the most minimal work and not with high quality. Examples include crappy alerts that never get changed; shared ownership of codebases lead to confusing team charters; extreme lack of integration+e2e tests (imagine hiring people just to navigate your UI instead of having suites of tests that can be run automatically); having to ask other people to do their job before you can do yours; the engineering onboarding has no clear ownership, so it does a very poor job at actually training new employees in a way that is practical; finally, people want to feel useful so seemingly there's a lack of documentation, so you have to consult the SMEs on things just so they feel useful (in reality, it's probably because repos have no clear ownership, and everyone who's know something about the repo has left the company already). Truthfully the list goes on, but in summary, the engineering culture at Credit Karma for the most part is complacent, and changes almost never happen.