You understanding isnt 100%
Previously the site had a dynamic house edge of 0% - 1% when the social bonus was 1%
After the social bonus was changed to 0.5% per round the dynamic house edge changed to 0.5% - 1.5%
The average is not calculated by (min + max / 2) but rather using previous betting data for the sample which ends up being a lot different
Possibly changing the wording Perchlorate has used might be of some help to avoid misunderstandings in future ?