Those numbers are misleading. IdenTrust has always been a small CA in terms of volume. The large percentage you see for them there is actually Let's Encrypt vol

Those numbers are misleading. IdenTrust has always been a small CA in terms of volume. The large percentage you see for them there is actually Let's Encrypt volume counted as IdenTrust because of the cross-sign. The Let's Encrypt percentage there is from sites not using the cross-sign. Add them together and that is basically Let's Encrypt's total volume, as IdenTrust itself is likely < 1%.