Thanks, you are right, the removal of ChromeCustomTab was done in 1.6.2 which never made it to production (it was only in beta). So effectively this change is new in 1.7.0. See also Discourse Hub doesn't open forums in their PWAs - #12 by md-misko for more details on why we made the switch, in addition to working without Chrome, this change also allows launching the PWA from DiscourseHub.
I am about to push a beta version with a fix for the crash issue. Will post a link here when that is ready.