Leclerc started from the pitlane in Barcelona after he qualified only 19th and the team opted to make changes to his car for the race.
However he was only able to rise to 11th place after his SF-23 again performed inconsistently across stints, even when running the same tyre compound.
Team-mate Carlos Sainz also struggled as he slipped from second on the grid to fifth at the chequered flag.
“The first stint we had the hard, which we expected to be a good tyre, but for some reason it was so bad,” said Leclerc.
“Like, no grip at all, especially from the front. The limitations were completely different to qualifying, so today we were more expecting this.
“Then for some reason [on the second set of hards we did] exactly the same thing and it feels really good. So for some reason we seemed to never really get in the right window of the tyre and when we do it's a bit of a surprise to us. So there is a lot of work we need to do.
“I think where we really need to put all our focus is to try and be at the peak of our tyres more often, and know how to manage them better.
“Two or three degrees makes a huge difference on balance, and this weekend we've been struggling, getting completely outside the window or in the window and happy with the car. So there will be a lot of work on that.”
Source: Autosport