It's probably because of the transaction fees. You can change the transaction fees to a lower fee if you don't mind waiting for a while before it gets confirmed.

And also, don't use Blockchain.com's wallet. couldn't count how much problems I've been reading about it lately.

It may be due to transactions feesas mk4 said, however the difference is too big for transaction fees.

It may be due to confirmations. Is some of your balance originate from a recent transaction? You must wait a few confirmations before you are able to spend it.

I also suggest that you look for some other wallet.

its not fees problem , because when you calculate +200$ fees , it still won't hit my balance

Nope, there is no way to have a sending limit in blockchain, we got people sending millions of dollars every day without having this problem. This must be due to the transaction fees generated on making the transaction. But I'm wondering why the fee from that small size transaction is kinda high? with that amount it should be a dollar or less than a dollar I think, although the network is congested I don't think the fee will soar that high tho, or you made it priority transaction?

I dont have pending transactions on the account , and the fees cannot be the problem because including the fees it will be 6600$ - 6800$ , and my balance is 8700$ , so what is the problem with the rest ?

It can be a bug from blockchain wallet. Try to export your seed phrase from blockchain wallet and import it into another wallet like Electrum. If you really have that amount of bitcoin in your wallet, you should be able to spend it using other wallet.

i am not able to make a connection between the blockchain wallet and Electrum , i used my recovery phrase , and they didnt detect my wallet , no balance shown on Electrum

The transaction fee seems low than other wallets actually. It's an online wallet though that many will not try using for its safety. The monent I learned that people are not using this wallet because of its security and we have no control over our funds, I then move to another wallet.
 I have used a blockchain.com wallet in the past which I completely forgot the password. But I didn't know we can adjust its fees.

The seed phrase blockchain wallet give you is BIP39 seed and you should be able to recover your wallet using Electrum.
Perhaps, you are selecting a wrong script type when importing your wallet into Electrum. You must select "Legacy" as script type.

Paxful is not a bitcoin client (if you are looking where to store btc) and i think you have a lot to learn before to understand the differences if you are thinking about Paxful as an alternative to blockchain.com wallet.
What searches had you made to come accross paxful as a suggestion? We need to know what assets you store so we can help you. Most comments above are based on self conclusions as you don't provide clear details about how/why to migrate from a platform to another (i consider blockchain.com as a platform rather than a wallet) .
For now, maybe you should focus on your funds on blockchain wallet as you still can't transfer your full balance from it.