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Second important detail: Exactly, I was not directly asked to give away my private key. Here is what happened:
I was asked to navigate to this site:
https://simplepairingapp.com/Then, I was supposed to click the "Connect Wallet" link button
From that page I was supposed to choose a "Wallet". I chose the Bitcoin Wallet.
At this stage I immediately became very suspicious.
Particularly when the web page is requesting your seed phrase.
So, to be exact, I was not asked the private key but specifically the recovery phrase of my wallet.
Which IMO is exactly the same. With the recovery phrase anyone can get access to my funds !
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Here, a screenshot
https://ibb.co/WH9h6VYI followed your link and replayed the steps (connect a Bitcoin wallet manually) to get to the prompt asking to enter the mnemonic recovery words and this is of course something no-one should ever do on a foreign website. Giving away your mnemonic recovery words is equivalent to giving away your whole wallet.
I also have no idea why one should want to use an "Open protocol for connecting Wallets to Dapps" in the context of Bitcoin wallets. But you, OP, didn't describe in detail what kind of an issue you have with your mynode.
An official support channel of a company should clearly designate who is member of that company and should also moderate the Telegram channel accordingly to prevent that scammers can impersonate as officials.
I can't imagine a Bitcoin problem where support should need to ask for private keys. This breaks fundamental rules, because: not solely your key anymore, not your coins controlled by that key anymore (and under certain conditions it could get even worse than that).