I'm not an expert on this but I buy nfts but "not" bidding but this question is also my question on bidding nfts that I never experience participate in.
Do you mind if I ask? Why did you buy an NFT in the first place? Is it something that you hope for an opportunity to selling it a higher price or you just simply like the aesthetics?
Their bids will be rejected by the contract if they do not have the required fund. It's as simple as you cannot send money that you do not have or below your actual balance.
Does that mean they give the required amount of their bid firsthand in the platform which is being escrowed by the platform itself using the contract? So, it's not just a plain text where they can withdraw their promises if ever the auction expires.
Do you have something to read where I can find an elaborate and technical answer to my questions? Perhaps, a general article on a website will suffice. Anyhow, thank you so much for the answer.