That is not an excuse :) Other solutions work fine even going past the 8 digit "limit".

"parsing" each command evey time is not efficient, and the test code do this a lot when jumping between lines.

This naive solution of mine (checking only rows) https://www.codewars.com/kata/reviews/599ac698a48343e7b90027e1/groups/63ab134c94973c0001c7aba0
passes all tests. This should not happen.

this is naive solution checking only rows, yet all tests from this kata passes. Poor kata.

ugly code but it's fast :)

for 10 digit string this gives Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 20480 bytes) in /workspace/default/_solution.php on line 20

for 10 digit string this gives Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 67108872 bytes) in /workspace/default/_solution.php on line 11

Failed asserting that two arrays are identical.
(strings vs integers in array)

with PHP8 you get Undefined array key -1 (line 8)

try getPINs('0123456789') with this soultion you get
Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 20480 bytes) in /workspace/default/_solution.php on line 34
so it's bad solution performance wise.

You don't need two iterations.

Your solution is faster but eats a lot of memory. At sandbox.onlinephpfunctions.com your solution with n = 5000000 runs of ouf memory.

you spoiled it with that return :)