When you join prop firm, the first and the most important question you should ask them are:
Do you need to pay "training fees", "platform fees" or "desk fee" or any money upfront? If the answer is Yes, you better Run.
If the answer is No, then ask your next question :
Do you need to contribute your own money as part of the "initial capital"?
If the answer is" yes", the next question to ask :
If you loss, are your money will be the first one on the line to get burned (e.g. if you contribute 5k and they contribute 95k, and if you loss 5k, they will automatically take your 5k and most likely will "fire" you). If this is the case, Run as fast as possible.
I bet 99% of prop form won't pass the above criterias.