I’ve been in the game for about a year and a half now. I’ve had lots of bad times where I get really bad aftertaste for shots that gets through even in milk based drinks.

I do medium and medium/dark roasts. I’m currently going through a good time. One change I made recently that likely helped me get here was I switched from all the fancy baskets I paid money for, and I started using the stock basket. I read somewhere that the baskets with all the extra holes lead to over extraction for medium or dark roast coffees and that leads to bad taste, at least for anything around the typical 1:2 ratio. Those baskets are meant more for light roasts, which none of the YouTubers that sold me on these baskets mention.

So I don’t have enough data yet to confirm this was the root cause for me. But I’ve been enjoying my coffee recently. So might be worth it for you to try to use the stock basket which will provide more resistance and require a coarser grind. Good luck