Exactly. Usually “friends” bring up the idea “venting” hoping that you would offer to help. How they respond to you backing out will tell you everything. I’d have a good story that they can’t argue with that’s short like “we were going over the finances and things are a lot tighter than we thought. I thought we could stretch to help you but we cannot. I’m sorry”. If they in any way try to convince you otherwise that’s a huge red flag to me.