Why compression rate of InfluxDB 2.0 Open Source much lower than InfluxDB 1.6 or earlier version?

I used to store stock quotation in influxdb, in version 1.7 seems compression rate is above10 times, but now in version v2.0 seems only 3 times, so it’s that true that the 2.0 Open source still not in good developing in compression? will be enhanced in future release?