The license does not allow removing the original license and purport that the code was created by someone else. It looks as if large parts of the project were copied directly from Spegel without any mention of the original source.
The license says (paraphrased) that you need to keep the original license file, which has the authors name. Even if you re-license it, you leave the old license there without touching it and put your new license next to it.
They did not follow that clause and deleted the original license and the original attribution.
I’m not a programmer, but I’d say if you copy large sections of a code, the original author belongs into the list of authors, not into the acknowledgement part, where you e.g. thank your significant other for their support, your collegues for their fruitful discussions or some society for their funding.
How much credit is needed to be counted as giving credit?
The license says (paraphrased) that you need to keep the original license file, which has the authors name. Even if you re-license it, you leave the old license there without touching it and put your new license next to it.
They did not follow that clause and deleted the original license and the original attribution.
A thanks does not necessarily imply credit.
In that case, I firmly disagree with Blue_Morpho’s assessment.
I’m not a programmer, but I’d say if you copy large sections of a code, the original author belongs into the list of authors, not into the acknowledgement part, where you e.g. thank your significant other for their support, your collegues for their fruitful discussions or some society for their funding.