python - Use of isinstance() can overwrite type

Use of isinstance() changed the class type of dict
Why is this happening? I know using builtins would prevent but I want to understand better why this is happening.

250     def printPretty(records,num,title='Summary:'):
251         import pdb; pdb.set_trace()
252         if isinstance(records, list):
253             print ("\n{}\n{}".format(title.center(120),"="*120))
254             table = list()
255             for i in records:
...
263         elif isinstance(records, dict):
264  ->         for key in records:

265                 if isinstance(records[key], Param):
266                     for i in records[key]:
267                         print (i)
268                 print ("")
269     
(Pdb) type(records)

(Pdb) type(dict)