If one owns the game on Steam, there's a tedious way to get the version of the game that still had the turn-based mode before it was overwritten/hidden. Doing so involves combing through
https://steamdb.info/ and looking up the Deadfire depots for the base game and DLCs that existed for less than 2 hours a few days ago.
If you want to play around with the turn-based mode as it briefly existed, here's how:
1. Enable Steam's Console: The quickest way to do so is to open the Run Window (Windows key+R), and typing in steam://open/console
You should see a new Console tab in Steam if successful.
2. You will need to manually download the depots for the base game and DLCs you own using the download_depot command with the Steam Console. They are as follows:
Base Game:
download_depot 560130 560131 737527484326782922
Main DLCs:
download_depot 560130 560134 9085111276035967401
download_depot 560130 812204 1952845592968314367
download_depot 560130 812207 92672211882417619
Other DLCs (including Critical Role):
download_depot 560130 560137 1478649678951473472
download_depot 560130 812214 5313336848894040769
download_depot 560130 812221 457086982652998859
download_depot 560130 812227 2447360910521227677
download_depot 560130 812231 1479624390411370622
download_depot 560130 812234 4550794723672811444
download_depot 560130 812244 677027520936962085
download_depot 560130 812247 740399630612379350
The above files will be saved to Steam's default installation directory\steamapps\content\app_560130. Ensure there's ~50 GB beforehand.
3. To enable the DLCs, copy the PillarsOfEternityII_Data folder from each DLC into \steamapps\content\app_560130\depot_560131
4. Run the game using PillarsOfEternityII.exe from \steamapps\content\app_560130\depot_560131. If everything went right, the main DLCs should be enabled on the title screen.
I only played around with the initial fight, but things seemed to be working normally, with no missing strings for the initiative window, ending one's turn, etc. I have no idea if the entire game is playable as such, but at the very least it gives a glimpse into how drastically different the combat feels in turn-based compared to the Deadfire of before.