I remember using SoloLearn a bit early on, but I found that for me at least, I retained a lot more of the concepts when I switched to watching courses on Udemy and making shit with the instructors as I watched. SoloLearn if I recall correctly has a lot of 'drag the right answer to the box' stuff and for my brain at least, it did not lead to retention.
For me to learn, I need to use it. I need to write the whole thing out. Maybe they got better about this in the years since I've used it, but if not and if you're finding concepts are hard to retain, try Udemy. They usually have sales on courses pop up regularly and you can get some for like 12$ (others for free).
I was looking into Udemy first but I never learn well from videos. I always fall off and kinda hate pausing and rewinding all the time. I prefer reading where I can stop wherever I want then just glance back at the last sentence instead of having to rewind to the right moment. Also this form is great for bite sized learning on the daily commute or during a 5 minute break. I'll probably have to resort to something else than SoloLearn when I get into the more advanced stuff though. Thanks for the tip!
For reading, I highly recommend Automate The Boring Stuff: https://automatetheboringstuff.com/. It's super good, though I still have to finish it. My python got sidetracked a while back and I never picked it back up.