I had a friend who was offered a biscuit and he took it and threw it out of the window.
The guy with the biscuits was offended and said "why did you waste the biscuit I gave you".
My friend said "you offered me a biscuit - it was up to me what to do with it".
Their should be a prompt from lichess in classical games that says are you still there? with a 30 second time to answer it. if you don't then it is a win or draw depending on what the other guy chooses. if you answer yes then the game continues.
sometimes i get so deep in thought that i forget and my time runs out.. or really low on time...
There will always be a way for toxic players to punish people for beating them. The ARE YOU THERE box could work, but if someone is deep in analysis it could be an unwelcome distraction. If they're letting time run out because I've a huge advantage, I just watch a video or surf the net. (computer only, dangerous with phones.) I'd recommending trying to remain calm and ask yourself how much of your energy the toxic player deserves. (NONE, if you're wondering)
But you'd be surprised how often they're just in the tank.
Just report them or say something in chat that you are going to report them. Just link the game in the report. As these players start to become banned there'll be less and less....