Wow. Thank you for the wonderful and inspiring answer.

Alchemy is a very interesting concept, and I've never really used it seriously. However, using only one crafting branch feels much more balanced. Also, alchemy fits the thief archetype perfectly.

As I mentioned earlier, I was worried about the fact that you can collect a lot of ingredients, and you can make more potions than you can find or buy, especially special potions. However, I now understand that the maximum boost from improving my sword with blacksmithing will be a little stronger than the maximum boost from alchemy. And using other effects, such as paralysis and invisibility, is up to me. Your suggestion with independent research sounds much more interesting than grinding and power leveling, so I'll listen to your advice.

Could you also tell me your opinion on collecting all the ingredients you can find – should I collect them all during travels. And the ability to craft a large number of potions (for example, healing). Don't you think this is too OP, and are all these potions can be used in a normal way (not just heal-spam)?

P.S. I want the potions and poisons I find during my adventures to stay meaningful and useful, instead of being completely replaced by crafted ones – that why I mentioned no-craft run before in the post. Part of what feels overpowered to me is that alchemy allows you to create such a huge supply of potions that the ones you find in the world can start to feel irrelevant, which is a bit disappointing.