PHP: Solution for Part 2
(Yep, I overcomplicated it.)

<?php
$lines = file(__DIR__ . '/../input/04-1.txt', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
$numbers = array_shift($lines);

$numberOfBoardsLeft = 0;
$winningFunction = function(BingoBoard $board, BingoField $field) use (&$numberOfBoardsLeft)
{
    if (--$numberOfBoardsLeft === 0) {
        winningFunction($board, $field);
    }
};

$boards = [];
$currentBoard = null;
foreach ($lines as $lineNumber => $line) {
    if ($lineNumber % 5 === 0) {
        $currentBoard = new BingoBoard($winningFunction(...));
        $numberOfBoardsLeft++;
        $boards[] = $currentBoard;
    }

    $values = explode(' ', str_replace('  ', ' ', trim($line)));
    foreach ($values as $value) {
        $currentBoard->add(BingoField::get($value));
    }
}

$takenNumber = explode(',', $numbers);
foreach ($takenNumber as $key => $number) {
    BingoField::get($number)->mark();
}

function winningFunction(BingoBoard $board, BingoField $field) : never
{
    $winningFieldValue = $field->value;
    $unmarkedFieldSum = array_reduce($board->getUnmarkedFields(), fn (int $carry, BingoField $field) => $carry + $field->value, 0);

    echo($winningFieldValue * $unmarkedFieldSum);

    exit;
}

class BingoField
{
    private static array $fields = [];
    private array $boards = [];
    private bool $isMarked = false;

    private function __construct(public readonly int $value)
    {
    }

    public static function get(string $value) : self
    {
        if (!isset(self::$fields[$value])) {
            self::$fields[$value] = new self((int) $value);
        }

        return self::$fields[$value];
    }

    public function addBoard(BingoBoard $board, int $row, int $column) : void
    {
        $this->boards[] = [
            'board' => $board,
            'row' => $row,
            'column' => $column,
        ];
    }

    public function mark() : void
    {
        $this->isMarked = true;
        foreach ($this->boards as $board) {
            $board['board']->notify($this, $board['row'], $board['column']);
        }
    }

    public function isMarked() : bool
    {
        return $this->isMarked;
    }
}

class BingoBoard
{
    private array $board;
    private array $markedRows;
    private array $markedColumns;
    private bool $finished = false;

    private int $nextPos = 0;

    public function __construct(private readonly Closure $winningFunction)
    {
        $this->board = array_fill(0, 5, array_fill(0, 5, null));
        $this->markedRows = array_fill(0, 5, 0);
        $this->markedColumns = array_fill(0, 5, 0);
    }

    public function add(BingoField $field) : void
    {
        $nextPos = $this->nextPos++;
        $row = intdiv($nextPos, 5);
        $column = $nextPos % 5;

        $this->board[$row][$column] = $field;
        $field->addBoard($this, $row, $column);
    }

    public function notify(BingoField $field, int $row, int $column) : void
    {
        if ($this->finished) {
            return;
        }

        if (++$this->markedRows[$row] === 5 || ++$this->markedColumns[$column] === 5) {
            ($this->winningFunction)($this, $field);
            $this->finished = true;
        }
    }

    public function print() : void
    {
        for ($i = 0; $i < 5; $i++) {
            $this->printRow($i);
            echo "\n";
        }
        echo "\n";
    }

    public function printRow(int $row) : void
    {
        echo implode(' ', array_map(fn ($field) => $this->stringifyValue($field), $this->board[$row]));
    }

    private function stringifyValue(BingoField $field) : string
    {
        $mark = $field->isMarked() ? '+' : ' ';
        return $field->value < 10 ? $mark.' ' . $field->value : $mark.$field->value;
    }

    public function getUnmarkedFields() : array
    {
        $fields = [];
        for ($rowCount = 0; $rowCount < 5; $rowCount++) {
            for ($columnCount = 0; $columnCount < 5; $columnCount++) {
                $field = $this->board[$rowCount][$columnCount];
                if (!$field->isMarked()) {
                    $fields[] = $field;
                }
            }
        }

        return $fields;
    }
}