Agus Salim

it’s happen to me, after update to 5.5
maybe you need to change (wp-config.php)
define(‘WP_DEBUG’, false); to define(‘WP_DEBUG’, true);

[Solved] remove + after _amount
it will be like this

$donated_amount = (float) give_maybe_sanitize_amount( $formatted_amount, array( 'currency' => $currency_code  ) );
			}
		}