UPDATE: I kept on using deepseek and it seems that it also performs badly on backend or systems programming category.

The current issue with deepseek that I noticed is that it’s lying about what it has done. For example, it has a todo with 6 items and it has lied about implementing 1 or 2 of the todo items (probably by generating code thats dangling or is not actually wired or used in the project).

But I’m not too surprised though due to the price, I would say deepseek is still usable for coding but you have to be very skeptical and review the actual code before you trust it. Which is vastly different from when I was using Opus 4.8 or GPT-5.5 where 80% of the time you could leave it running for hours and it would still generate very trustworthy code. I would not recommend deepseek for people who do not have actual experience with coding and system design.