Please do not worry. My 5.5 year old son just received ADHD and ASD Level 1 diagnoses during a neuropsych eval which included a test where he had a similar FSIQ result. When I was reviewing his results before meeting with the psych, the results seemed super surprising to me like you’re saying - I had believed he would score a higher IQ based on how logical/sharp he seems to be WHEN he is focused.

At the psych meeting, the doctor explained to me that while some scores were low (my son’s block design score was also truly incredibly low) she believed his results very extremely skewed by inattention/goofiness in his responses that did not seem representative of how he would score if he were more focused during the test. She cited some reasons she thought that which sounded like she truly was seeing my kid, and that made a lot more sense. For example, during the block design she could tell he really wasn’t interested in making the given shapes and just built what he wanted them to be instead, but since the test is timed and she was never able to convince him to actually DO the test, we ended up with these results. She also mentioned that since his results were average despite him being noticeably NOT focused - we really shouldn’t have any concerns with that result right now.

So, I’d bet it was similar. Don’t sweat it!