If anyone still wonders about this, when I bought mine this week (January 2025) the battery was 6 months old.

Great tutorial, works like a charm. The battery sold by ifixit works great too on my OnePlus 5T. In my case, the metal cover on the upper main Flex (step 14) was sticked to the flex so I just removed the metal cover and the flex at the same time. I would not recommend separating them. Also, the original battery was really hard to remove because of the adhesive and I had to bend it to remove it... a bit dangerous. Can't really scratch underneath either since there's a flex there, just be careful or use a heater.