This release is primarily bug-fixing and upgrading to Teiid 8.9 runtime which required some updates to the JBTools Integration stack 3rd party components that just got upgraded and made available yesterday.
The plan is to have a 9.1 Final next week and to move on to 9.2 Designer work including upgrading to Teiid 8.11. The release date for 9.2 is targeted for early August.
Barry