Most orgs I've worked for are so growth and product-focused that if you try adjusting your estimates to include proper testing, you get push back, and you have to ARGUE your case as to why a feature will take two weeks instead of one.
This is the thing I hate the most about work, having to ARGUE with PMs because they can't accept an estimate, there's often some back-and-forth. "What if you do X instead?" "Team Y (always uses hacks and adds technical debt with every single feature they touch) did something similar in two days." But we're just communicating and adding transparency so that's good and it certainly doesn't matter that it starts taking up 4+ hours of your time in Slack conversations and meetings of people 'level setting' 'getting on the same page' trying to help you 'figure out' how to 'reduce scope' etc. etc.
Also, I think testing via unit or integration tests should be standard regardless, and that isn't what I am thinking about here. I'm thinking about QA, the way QA does it. You hammer your feature with a bunch of weird bullshit like false and unexpected inputs, what happens if I refresh the page in strange ways, what happens if i make an update and force the cache to NOT clear, what happens if I drop my laptop in a dumpster while making the request from firefox and safari at the same time logged in as the same user, what happens if I turn off my internet in the middle of a file upload, and so on. When devs say that devs should be responsible for testing, they usually mean the former (unit and integration tests), and not this separate skillset of coming up with a bunch of weird edge cases for your code. And yes, unit tests SHOULD hit the edge cases, but QA is just better at it. You usually don't have engineers testing what happens when you try sending in Mandarin characters as input (unless they live in China, I guess). All of that effort should bring up your estimates because it is non-trivial. This is what getting rid of QA means, not happy path end-to-end testing plus some unit and integration tests.