I'd downloaded a tested ALT Regular ISO images (both KDE and GNOME, build published 18022026) from here:

https://nightly.altlinux.org/sisyphus/tested/

And try to install both of them with below partitioning scheme (UEFI SecureBoot was active):

/boot/efi (ESP, FAT32)
/boot (ext4)
/ (XFS)
[swap]
/var (XFS)
/var/log (XFS)
/var/log/audit (XFS)
/opt (XFS)
/tmp (XFS)
/home (XFS, LUKS2 encrypted)

And installer hanged after partitioninig for a long time, then an error was occured.

When I tried the same partitioning with EXT4 filesystem instead of XFS, it was fine. The system was correctly booting up, and running well.

Before I did the same partitioning with XFS and LUKS many times, and no errors with previous installs were occured. Maybe it's something wrong with installer version (from 18022026 iso image)?

BTW, when I made a separate /tmp partition, placed in real FS, not in memory, I got two instances in /etc/fstab, both tmpfs and ext4 types.