[Bug]: "user_names" show "broken"

What happened?

After I updated my Xubuntu to version 25.04, if in my conky.conf I put into "conky.text" a row to display the users logged in, I obtain the string "broken". My conky.conf does a heavy use of Lua, but until the updating all it was OK, so I don't think that the problem is in my config file. However I'll show the relevant part of my config file but I'll not clutter this post with all the Lua functions that I use to prepare images and data. Into the log I don't see any error, even when I launch conky with option -DD.

Am I doing something wrong or this is really a bug/compatibility issue with latest Ubuntu? Thanks for any help

Version

1.22.2

Which OS/distro are you seeing the problem on?

Ubuntu

Conky config

...
SHOW_KERNEL_IMAGE = 'yes'
IMAGE_KERNEL_POSITION = '0,0'
IMAGE_KERNEL_SIZE = '48x48'
SHOW_USERS = 'yes'
...
conky.text = ''
	-- ***** HEAD SECTION
	.. '${if_match "' .. SHOW_KERNEL_IMAGE .. '" == "yes"}'
	.. '${image ' .. image_kernel .. ' -p ' .. IMAGE_KERNEL_POSITION .. ' -s ' .. IMAGE_KERNEL_SIZE .. '}'
	.. '${endif}'
	.. full_kernel_string
	.. full_distro_string
	.. '${if_match "' .. SHOW_USERS .. '" == "yes"}'
	.. '${color2}${voffset 5}USERS:${color0} ${user_names}\n'
	.. '${endif}'

Stack trace

Relevant log output

conky: desktop window (0x1a00017) is subwindow of root window (0x209)
conky: window type - normal
conky: drawing to created window (0x7600002)
conky: drawing to double buffer
conky: forked to background, pid is 31517
conky: FOUND: wayland
conky: FOUND: x11
conky: FOUND: http
conky: FOUND: file
conky: FOUND: ncurses
conky: FOUND: console
conky: 'xubuntu' x11 session running 'XFCE' desktop