Again - I think that your confusion just derives from people (including me) having problems to translate the german legal terms and mixing two sets of problems. I tried to clarify in the following picture. Your problem is certainly one of row (1). If you have decided you want to become self-employed, you still will have to deal with the differentiation of row (2).

If you are self-employed:
- you only work (and get paid) when clients hire you
- you are not protected by "Arbeitsrecht"
- you have to keep books and take care of taxes (Inc.tax & sometimes VAT) and insurances
- you dont earn a right to "Arbeitslosengeld I"
...
Reasons, why the law might consider you to be "Scheinselbständig":
- you have to do what, when and where your client/employer tells you to do
- you are an integral part of your client/employer s business
- keine Unternehmerinitiative, kein Unternehmerrisiko,
- fixed payment
- you are not allowed to send someone else to do your work in your place
- the amount of work is controlled by someone else
...
The negative consequences of being considered "Scheinselbständig" mostly strike the client/employer. So if he is offering you that kind of contract, he is either very stupid, will never pay you as much as you should get or has other sinister plans...
Carm do you really have a choice between doing the same job as a freelancer or as an employee? Or are you an employee already and are offered to do the same thing now as a freelancer?
(Btw I just scribbled that down in a few minutes. I might have made mistakes. My perspective on "Scheinselbständigkeit" are subjective. If at all you should just use them as a hint for further investigations or a consultation with a tax consultant or expert in "Arbeitsrecht".)