Session recording flushed-size tracker no longer leaks across tabs

1.390.2

Patch Changes

• #3868 a5dd54a Thanks @pauldambra! - fix(replay): scope the session-recording flushed-size tracker to the session

  $sdk_debug_replay_flushed_size was stored as a single device-global value in persistence and only reset on an in-page session rotation, so it leaked across page loads and tabs and over-counted on returning visitors. The tracker now keys the running total to the current session id, so a new session starts from zero and a fresh load reading an ongoing session sees the correct total.

  The internal persistence key backing this counter ($sess_rec_flush_size) was also unintentionally attached to every captured event as a super-property; it is now marked hidden so it no longer ships on events. The value remains available on session-replay debug events as $sdk_debug_replay_flushed_size. (2026-06-17)