A commit was made to the AOSP gerrit a couple of days ago which could be hinting at removal of the 4GB video recording file size limit on Android devices. A 64-bit offset for MPEG4Writer has been proposed to overwrite the current 32-bit setting. This means that file sizes over 4GB may be saved as one, whereas presently, recordings over 4GB are split up into more than one file.
While testing, a 32GB file was composed using MediaMuxer which played back fine on the phone as well as a Linux workstation. In another test, the entire phone storage was filled using MediaMuxer and MediaRecorder separately, though the amount of storage on that tested phone hasn't been disclosed.
If the commit goes through, the change will be a welcome one for Android users as phones' camera qualities continue to improve leading to larger files. Nowadays, quite a few phones sport the 4K30 video recording feature, and with that in mind, it's understandable as to why such a limit could be preventing users from recording longer videos as one file. Upcoming Snapdragon 865 devices as well as other high-end phones are likely to feature 8K recording, so removal of the 4GB file size limit should be high on the priority list for Android 11 developers.