It's a feature, not a bug.
Google debuted Digital Wellbeing last year, with Android Pie. And it now appears to be slowing down the Pixel 3a, as well as older Pixel smartphones. Digital Wellbeing is designed to be a feature that gets you to use your smartphone less, so this sounds a bit more like a feature rather than a bug. If you're smartphone is getting slower, then you're going to use it less.
Many Pixel users over on Reddit have complained about how slow their smartphones have gotten. After having tried many things, it appeared that disabling Digital Wellbeing made the phones fast once again. For many people, disabling Digital Wellbeing isn't going to be a big deal, considering the fact that most people don't really care how much time they've spent in the Twitter app today. Or to see how many notifications they've gotten today.
There are a few useful features included, like the Flip to Shhh feature, but most people don't use that either.
Google has been promoting the Digital Wellbeing feature, essentially since it was announced at Google I/O last year. As Google wants people to use their smartphones less, and actually interact with people they talk to and see every day. It's also a feature that Apple has included in iOS, starting last year, and Facebook has even added it to its app and the Instagram app. As the major tech companies know that users need to spend less time looking at their smartphone every day. Considering it's not good for our eyes, that's a good thing.
It's a little strange that Pixel 3a users are having issues with Digital Wellbeing on their smartphones. While it does affect the Pixel 3, it's not to the same extent. It's also not affecting all Pixel 3a smartphones. For example, our Pixel 3a XL unit that we are reviewing right now, isn't having any performance issues. We disabled Digital Wellbeing just to make sure, and it appeared to be just as fast with it disabled as it was with it enabled.
This just adds on to the many issues that Pixel smartphones have had in this generation of releases. The Pixel 3 and Pixel 3 XL had a ton of issues when those launched back in October, with very few of those issues actually being fixed at this point. And now the Pixel 3a hasn't even been available for a week, and users are finding a ton of issues with the devices already. Google could fix these with updates though, but given how well that worked out with the Pixel 3, I wouldn't count on it. Luckily, the biggest issue with the Pixel 3a is relegated to turning off Digital Wellbeing. Which will likely save you some battery life too.
The Pixel 3a and Pixel 3a XL are available for purchase now, with prices of $399 and $479 respectively. These aren't quite flagship smartphones, but they are pretty good options for those looking for a smartphone under $500 right now. Especially considering it does have the famous Pixel camera built-in.