Perhaps have a look at the Canon 40mm f/2.8 STM pancake lens instead? It might look a bit like a toy but it's reputedly sharper than the latest Canon 50mm STM lens, plus it gives you a really natural looking field of view on a full frame camera: Over the years I've often found 50mm lens (on an FF camera) is a bit too 'tight' in its field of view when trying to frame a shot, but 35mm would have been too wide. However, I find that 40mm hits the sweet spot in between.
So maybe look at a good, used, Canon 40mm STM pancake lens (with a realistic target price of less than £100 from a reputable dealer with 6+ months warranty) and see how you go? At that price, even if you dislike it (which I doubt will be the case) then I think it's unlikely you'll drop more than £20 (if that) if you choose to sell it on (providing you've not trashed it!). After all, how much would you get for a used Yongnuo 50mm if you find you don't like it?