import re
pattern = r"\b\d{8}\b.*?(?=\s*(?:\b\d{8}\b|$))"
s = "12345678 abcdefg 37394822 gdzdnhqihdzuiew 09089799 78998728 gdjewdwq"
print(re.findall(pattern, s))
aW1wb3J0IHJlCgpwYXR0ZXJuID0gciJcYlxkezh9XGIuKj8oPz1ccyooPzpcYlxkezh9XGJ8JCkpIgpzID0gIjEyMzQ1Njc4IGFiY2RlZmcgMzczOTQ4MjIgZ2R6ZG5ocWloZHp1aWV3IDA5MDg5Nzk5IDc4OTk4NzI4IGdkamV3ZHdxIgoKcHJpbnQocmUuZmluZGFsbChwYXR0ZXJuLCBzKSk=