Can’t access the class variables from a event handler

I am making a web application for arranging seats, and I have written these codes:

class SeatMap {
    constructor (parentElement) {
        this.#createSeats();
    }

    #createSeats () {
        this.seatList = [];
        for (let a = 0; a < this.row; a++) {
            for (let b = 0; b < this.column; b++) {
                this.seatList[a].push(new Seat(this,a,b));
            }
        }
    }

class Seat {
    constructor(seatContainer, rowNum, colNum) {
        this.seatContainer = seatContainer;
        this.seatTB.addEventListener("keydown", this.#keydownTB);
    }

    // Key Events Handler
    #keydownTB (event) {
        const seatContainerConector = this.seatContainer;
        if (event.key === "ArrowRight") {
            console.log(seatContainerConector); // Undefined
        }
    }
}

// I only wrote codes related to the problem here.

However, console.log(seatContainerConector); just gives me back undefined.
I have tried to delete const seatContainerConector = this.seatContainer; and use console.log(this.seatContainer); instead, but it didn’t work.
How can I solve this?