[2022] Cannot save game in multiplayer when team name contains certain characters

I just played a 2-player online multiplayer session, with both humans controlling one player. We named ourselves [Die "Gerechten"] (not including the "[", characters, but including the " characters).
The first auto-save after a few minutes failed and created the "Das Spiel konnte nicht gespeichert werden" error message. Manually saving also did not work - regardless of the chosen name of the savegame.
Anno 1800 did not warn us that the chosen name was problematic at all.

Starting a new game with another player-name (identical configuration except for world-seed, same 2-humans multiplayer, just with a different faction-name without any special characters) then allowed saving again, so it doesn't seem to be a problem with the installation and just the chosen name string [Die "Gerechten"] (again, without the "["/"]").

All DLCs (except Season 4 & Anarchist) were activated, the game is not modded. One AI was active (Willie Wibblesock).
There is enough disk space available (>100 GB free). Antivirus is Windows Defender, running on Win10 21H2. The game and OS language are set to German.