Match lost due to cheating..even tho i exactly didn't(claim victory or draw situation)

Easy solution is just take the win. Problem solved.

If the opponent's rating is affecting you in such a way, try using Zen mode.
It hides all distractions including the rating.

The decision is for you to make and if you think deciding is tough, you can simply wait for your opponent to return.
The timer would be ticking for him anyway.

Hopefully this is a one time incident; do not open the analysis board(with the engine On) next time while playing, Lichess automatically detects it. It wouldn't be fair to the other player if Lichess decides the game by providing an evaluation.
With time, you must be able to evaluate positions on your own. It's upto you.

Suppose he came back in the moment where you had seen the valuation together with the winning move. What would you have done? Resigned?

Answer to your question: Yes, rely on your own evaluation. If you win thus, although "objectively" it is not won, then this is your opponent's bad luck.

I always claim victory even if I am losing

Haha the display of morality on here is astonishing.
Here I am, hoping Lichess implements an automatic claim victory setting 😛

@Raven_-v It happened to me in my old accounts,too. My opponent offered draw and i opened Analyze Board for see who has an advantage ( LOOL) Then it said Cheat detected.
I was dumb, but now i am not xD
Do not open analyze board during game.

Too many cheat in online chess including the highest rated players. Humans are so totally corrupt. Lichess is no exception. It seems as if its Liechess. that gets people ahead. The ratings on this site are so skewed because of this.

I always take the win bc if I get disconnected my opponent would take the win too ... it sucks but what do against disconnects? Your time would run out anyway if you can't fix it within the cooldown.

I learnt my lesson to not play on train.