Steam says during game update "not enough free disk space" even though there is clearly enough space

$ df -h | grep -Ei '(/|games|on|tmp)$'
Filesystem              Size  Used Avail Use% Mounted on
/dev/dm-0               220G  178G   31G  86% /
tmpfs                    16G   25M   16G   1% /tmp
/dev/mapper/luks-games  229G  205G   12G  95% /mnt/games

Update size is 1.4GB (Cyberpunk 2077), so everywhere should be enough space. What is Steam doing and why 1.4GB update can’t be downloaded to a device with 12/16/31GB of free space? Why does it need more space than the update itself, at least 9 times more?

I already tried clearing download cache, verify game files and checked permissions are ok (since than update for an other game was successfully done, so there should be no issues with download or library folder). Steam doesn’t even report where is not enough space.

How to troubleshoot/fix this? (I don’t want to redownload any big game, or remove any game already installed.)