It looks like you are hitting the rate limits as explained here.
If you are using Make.com, the easiest way to avoid it would be to just set a timeout (a block that “waits” for a few seconds) between each query. You can find other possible solutions in the link above
As the error is quite clear, the odd part, is that it happens after creating only 32 subitems. Why is this? I ran similar queries in the past and they all worked fine.
This will depend on how many points each of the mutations take, and also if you are using the API for any other operations. It looks like the amount of queries/mutations you are using multiplied by each operation’s complexity points usage, adds up to the limit. The number of queries/mutations itself is not relevant here, but the addition of points used is