Hello @c_silvio and Welcome to the Make Community!
There may be other ways to handle this, but here’s one…
In your filter, you use replace to replace the first digit found with something else, then in that same filter do not allow the value to pass if it contains that same “something else”. For example:
For “donotpass”, choose a string that isn’t likely to appear in your text.
In your example this would turn “Test123 or Test 123 “ into “Testdonotpass23 or Test 123 “ and since it now contains “donotpass” the filter will not let it pass!