import re
test = 'Valid items: (aaa.com; bbb.com); Invalid items: (abc.def.com;); Valid items: (foo123;); Invalid items: (bar123;); Valid items: (1234; 5678; abcd;); Invalid items: (hello; world; 1212; 5566; aaaa;)'
results = []
for s in re.findall(r'Invalid items: \((.+?);\)', test):
results = results + s.split(r"; ")
print(results)
aW1wb3J0IHJlCnRlc3QgPSAnVmFsaWQgaXRlbXM6IChhYWEuY29tOyBiYmIuY29tKTsgSW52YWxpZCBpdGVtczogKGFiYy5kZWYuY29tOyk7IFZhbGlkIGl0ZW1zOiAoZm9vMTIzOyk7IEludmFsaWQgaXRlbXM6IChiYXIxMjM7KTsgVmFsaWQgaXRlbXM6ICgxMjM0OyA1Njc4OyBhYmNkOyk7IEludmFsaWQgaXRlbXM6IChoZWxsbzsgd29ybGQ7IDEyMTI7IDU1NjY7IGFhYWE7KScKcmVzdWx0cyA9IFtdCmZvciBzIGluIHJlLmZpbmRhbGwocidJbnZhbGlkIGl0ZW1zOiBcKCguKz8pO1wpJywgdGVzdCk6CiAgICAgcmVzdWx0cyA9IHJlc3VsdHMgKyBzLnNwbGl0KHIiOyAiKQoKcHJpbnQocmVzdWx0cyk=