When I use Google PageSpeed to evaluate my website, I receive 100 ratings. Furthermore, essential web vitals also indicate passing.
However, why am I receiving a N/A for First Input Delay and Interaction to Next Paint?
Does my code have a problem, or do I need to adjust certain settings?
Not every page will receive interactions. A blog for example might have visitors open it, read it, and then close it without "interacting" with the page by clicking. Note: scrolling does not count as an interaction for FID or INP.
In these cases PageSpeed Insights will show "N/A". Note however in your screenshot that the Core Web Vitals assessment is still shown as "Passed". Lack of FID or INP data is not treated as a failure and simply "Not applicable".