I am using Avaya Client SDK for JavaScript, Release 4.15.0.0 - it is the latest one. It uses "plan-b" SDP format. Dropping support for Plan
B is targeted for Chrome M93 (Canary: July 15, 2021; Stable: August 24, 2021).

Is there any information about when Avaya Client SDK for JavaScript will move to the "unified-plan" SDP semantics?

On JSCSDK, changes for transitioning to unified plan from plan B, was introduced in the 4.8.0.5 release.

AAMS has updates for unified plan SDP semantics in 8.0.2 SP7 (exact build number to be released by May 14th).

A 4.8 version of the JavaScript Client SDK has been released and is available on the downloads page as v4.15.0.1 of the Client SDK. This version removes the specification of plan B SDP semantics.

Due to a change coming in Chrome 96 that causes Chrome to now throw an error when plan B has is specified instead of just ignoring it and using unified plan semantics, all calls will fail with earlier JavaScript Client SDK versions. It is recommended to upgrade to the new version in order to avoid a service interruption.