can they be hacked, and the funds stolen, do they have a special wallet where they keep all the btc ? how do they work exactly?
can they suddenly decide to hold your btc, or restrict you or prevent you from sending or receiving bitcoin ? if you don't provide id or for whatever reason ?
do you own your btc (menmonic) with them or is it in their control?
thanks
blockchain.com hosts a non-custodial wallet service. they don't "hold" your BTC. that's why they can't recover your wallet for you if you lose your key/password. your seed can be used to recover your coins to any other HD wallet.
so it's not as bad as 3rd party web wallet services that actually control your BTC. but there are still some security hazards. you are prone to various MITM attacks when you use a trusted online service like blockchain.com to sign and push transactions.