Why does a 1300-1400 chess.com player feel stronger than a 1700 lichess player?

@miop when you create a new account, you can select the expert level, so that all of your ratings start at 1800.

@seanysean that is only in the V3 version
at the other you must start on 1150

It's not a one-to-one comparison. A Lichess player is very very roughly a few hundred points lower on FIDE/USCF/chess.com, but it really gets closer near the top, for one. Some examples:
Kingscrusher is 2170 FIDE, 2297 Lichess classical.
TheLlamaLord is 2042 FIDE, 2400 (!) Lichess classical. You should not try to take someone's Lichess rating, and try to squeeze out a FIDE rating from it. Look at their games, and surmise how good they are.

Different rating systems?
Lichess uses Glicko-2, while chess.com uses elo (?).

Chess.com uses Glicko. Probably Glicko 1, they don't specify.

Yes, chess.com uses original glicko, lichess uses glicko-2. The difference has nothing to do with that and entirely to do with the starting ratings. The starting rating on lichess is 1500, and the starting rating on chess.com is 1200. The average rating will drift (usually downwards) over time on both sites, but that 300 point difference crushes any subtle drift that will occur over time.

because the are many good players hiding behind those low ratings, using site as form of relax probably; and there are many bad players that use engine assistance ( just see how many accounts chess.com close daily )

I thought that you can choose your chess.com starting rating by pressing beginner, intermediate, or expert.

@nobody22 You can, I've been trying to explain that.

That's a new feature. The vast majority of players on chess.com signed up before that was a choice. A new change to the starting rating (which probably still averages out to 1200, though I don't know the details of that) would have almost no effect on the pool until years have passed. And even that depends on what people select on average.