The meaning hasn't changed. The thing is that you can't translate "ein Kredit" as "a credit" in many situations. One reason for this is that "a credit" does not only mean "ein Kredit" but also other things, e.g. "a sum of money paid into a bank account", "a payment that sb has a right to for a particular reason: a tax credit"
(OALD), or a letter of credit. (Search Leo for "credit" to see more.) For example, we say "I would like to have a loan/overdraft" and not "I would like to have a credit". As this is the meaning that comes up the most often in lessons, it would probably be easy to get the idea that you should never translate "Kredit" as "credit", but that's not right.
There are some situations where you can (and have always been able to) use the word "credit" for Kredit (see Leo under "Kredit").
Hamblock/Wessels Großwörterbuch Wirtschaftsenglisch:
Kredit - credit, loan, advance, accommodation, advancement, overdraft, facility
(This dictionary has 2 pages of phrases with "Kredit", variously using credit, loan etc. depending on the phrase)