Regular Expression – have at least n different digits

I want to use regular expression to check if the numbers have more than 2 different digits. For example, AB1000002 is allowed but AB1000000 is not allowed.

My question is similar to this one but seems to be more complicated.
Reference: Regular Expression- have different digits

Thanks in advance!

I am not good at coding, I have tried to fix this problem but what I can do is just simply make the check of "at least 1 different digit" start from the second number…which is a bit stupid sorry I know…
\d(\d)((?!\1)\d)+

>Solution :

Why to use regular expressions when the set() does it easy and efficiently?

for st in ["AB1000002",  "AB1000000"]:
    if len(set(st[2:])) > 2: # remove AB and run set on numbers
        print(st)

AB1000002