Long story short, I transferred $12 for a start into the kucoin account with a transfer that shouldn't take more than 2hrs to complete on normal circumstance but waited for longer hours without receiving nothing. I was moved to crosscheck their deposit limit again only to discover that as bitcoin price keeps rising that's how their deposit limit commensurate with the bitcoin price rise. So at the moment the deposit limit was above $12 and that was how I lost those coins to kucoin.
This is happening to people not only you, especially when Bitcoin price is going up. Try and always send above the minimum deposit limit, you can only know the deposit limit if you pay attention and checked properly before sending. Exchanges are making lot of money from these kinds of transactions and you cannot hear them addressing the issue for ones because they are benefiting from all these failed transactions as it is not refundable.
This is why before depositing coins to any CEX even if you had known before what their deposit limit was in the past months or so, do your due diligence by rechecking if you're sending a little amount of coins especially now that the bullrun season is here with bitcoin price on an uptrend many CEX will likely want to take advantage of that area of their policy to as @plaguedeath pits it "legally steal" customers money.
Yes, they are always happy if customers make such mistakes, and instead of them to disallow the transaction since it is below the deposit limit of that exchange, the exchange will receive the money.
To avoid all these, I do use stable coin because of charges and I also used tron to send through exchanges because of the low transaction fee.