Writing to flash filesytem gets slower as the file size grows

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I'm trying to write logs from IMU to flash file system, for that I'm using LittleFS. I've one task polling from IMU and creating a char buffer (this task is running at 32 Hz), the IMU task then sends the char buffer to the logger task with the help of a queue. Things are running smooth for the first couple of minutes. As soon as the file size grows to over mb, writing speed seems to slow down and the queue starts to fill up and eventually fills up and starts missing some of the incoming values.

Code snippet for IMU task

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static void imu_task(void *pvParameter)
{
	TickType_t xLastWakeTime = xTaskGetTickCount();
	const TickType_t xFrequency = (31); // delay for mS

	for (;;) {
		mpu6050_get_acce(mpu6050, &acce);
		mpu6050_get_gyro(mpu6050, &gyro);
		imu_values.ax = acce.acce_x;
		imu_values.ay = acce.acce_y;
		imu_values.az = acce.acce_z;

		imu_values.gx = gyro.gyro_x;
		imu_values.gy = gyro.gyro_y;
		imu_values.gz = gyro.gyro_z;
		
		IMUvalues[0][marker] = imu_values.ax;
		IMUvalues[1][marker] = imu_values.ay;
		IMUvalues[2][marker] = imu_values.az;
		IMUvalues[3][marker] = imu_values.gx;
		IMUvalues[4][marker] = imu_values.gy;
		IMUvalues[5][marker] = imu_values.gz;

		snprintf(spiffs_buffer, sizeof(spiffs_buffer),
			 "%llu,%.1f,%.1f,%.1f,%.1f,%.1f,%.1f,%.1f,%d,%d,%d\n",
			 esp_timer_get_time() / 1000ULL, IMUvalues[0][marker], IMUvalues[1][marker],
			 IMUvalues[2][marker], IMUvalues[3][marker], IMUvalues[4][marker],
			 IMUvalues[5][marker], freq, sos, leg_client_connected, voltage_1);

		ESP_LOGI(tag, "IMU task high water mark %d", uxTaskGetStackHighWaterMark(NULL));

		if (xQueueSendToBack(data_queue, spiffs_buffer, 5 / portTICK_PERIOD_MS) != pdTRUE)
			ESP_LOGW(tag, "Could not send to queue");

		vTaskDelayUntil(&xLastWakeTime, xFrequency);
	}
}

Code snippet for logger task

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static void logger_task(void *args)
{
	char incomming_messages[1024];

	esp_vfs_littlefs_conf_t conf = {
		.base_path = "/littlefs",
		.partition_label = "storage",
		.format_if_mount_failed = true,
		.dont_mount = false,
	};
	
	LOGGER = xTaskGetCurrentTaskHandle();

	for (;;) {
		if (xQueueReceive(data_queue, incomming_messages, 5 / portTICK_PERIOD_MS) != pdTRUE)
			continue;
		else {
			uint16_t FreeSpace = uxQueueSpacesAvailable(data_queue);

			printf("Free Space on queue: %d\n", FreeSpace);

			int remaining_space = filesystem_get_free_space(conf);
			if (!remaining_space && f != NULL) {
				fprintf(f, "%s", incomming_messages);
			}
		}

		if (uxQueueMessagesWaiting(data_queue) == 0) { // no message? take a break
			vTaskDelay(10 / portTICK_RATE_MS); // delay 15s
		}
	}
	vTaskDelete(NULL);
}

Queue defined as :

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	data_queue = xQueueCreate(100, sizeof(char) * 1024);