Thank you for the answers, guys. Believe me, I keep asking myself how could I be so idiot to trust in that network.

I forgot to show the wallet:
https://www.blockchain.com/explorer/addresses/btc/14AKAd16AEZZoW3dp4KEyANMJ3G5bPCrwE

It looks like someone stole from several wallets, mine was just one of that.

I will buy a hard wallet now. I suppose I was lucky, I have more BTC in the broker and was about to send them to my wallets - I generate several using the same way. Just this one had BTC, and, of course, I will never use them again.

A few more infomations: I've never said that my work's network was 100% safe or that I trust 100% in the IT guys (I'm not in the IT team). I just said that I don't think that it was the problem and, for the safe of arguments, try to find other security problems.