New mac strange behaviour on one macro

I had an Intel mac and all was fine, switched to a new M3 MBP and the below macro behaves non-deterministically — the output is never in the sequence in which I would expect. Direct connection to the MBP


Strangely a similar one below works fine… thoughts?

okay adding

set keystrokeDelay 10

to the macro sorted it
Strange that it only transpired on the apple chip.