From this reply, it seems that it has nothing to do with `/effort`: https://github.com/anthropics/claude-code/issues/42796#issue...

I hope you take this seriously. I'm considering moving my company off of Claude Code immediately.

Closing the GH issue without first engaging with the OP is just a slap in the face, especially given how much hard work they've done on your behalf.

I commented on the GH issue, but Ive had effort set to 'high' for however long its been available and had a marked decline since... checks notes... about 23 March according to slack messages I sent to the team to see if I was alone (I wasnt).

EDIT: actually the first glaring issue I remember was on 20 March where it hallucinated a full sha from a short sha while updating my github actions version pinning. That follows a pattern of it making really egregious assumptions about things without first validating or checking. Ive also had it answer with hallucinated information instead of looking online first (to a higher degree than Ive been used to after using these models daily for the past ~6 months)

Gotcha. It seemed though from the replies on the github ticket that at least some of the problem was unrelated to effort settings.