Samsung has started to distribute One UI 3.1.1 to all Galaxy Tab S7 variants, including the Galaxy Tab S7 FE. The update is reaching 5G and Wi-Fi models, for reference. The rollout is already underway in Europe, so it should not take too long for it to reach other regions. Typically, new updates take anywhere from a few days to a few weeks to reach all eligible countries.
T976BXXU2BUI1 arrives as a 1.37 GB download and contains the September 1st security patch. According to the changelog, Samsung has added the option to 'remaster' photos, another way of saying that the Galaxy Tab S7 series can automatically enhance images. Additionally, the update brings improved Edge panel usability by virtue of a new pin feature. Accordingly, you can now pin apps to the Edge panel, which should no longer blur the background screen when it is active.
Moreover, One UI 3.1.1 adds a triple split view function as part of a multitasking overhaul. Previously, One UI could only display two apps side-by-side, despite the size of the Galaxy Tab S7 series' displays. One UI 3.1.1 also allows you to switch between pop-up view and split-screen view, while the latter can now be activated by dragging the screen. As Samsung notes in its release notes, it is a good idea to backup your data before installing T976BXXU2BUI1; One UI 3.1.1 should not affect your data, though.
Source(s)
Samsung via Tizen Help