Apple serial numbers follow the model through refurbishment, so a serial built in Austin in March 2019 means it really is that young. As to whether they solved the early issues, well, that I can't speak to, and does kind of make me want to get AppleCare+ to fish for a new free Pro or Studio 😉 I wouldn't ponder buying this if I needed it to make my livelihood on, but to replace a very tired moderately built 5,1 that doesn't get pushed anywhere near it's limits.....
But for the price, the whimsy is sufficient to keep me happy, this isn't a work machine, it's my goof around home computer editing pics and videos of my kids.