ChatGPT 4 reduction in capability

Hello,

Just wondering if there is some information on why ChatGPT 4 seems to have lost some of the capability it had when it was initially released? Is this due to performance issues and outages and trying to fix them?

Really seems easier to get useful output out of version 3.5 at the moment with a little extra prompting, but recently version 4 is lacking the magic it seemed to have when I started initially using it and the output is a lot less useful.

Thanks,
Alex.