Problem with the AUCTeX configuration

[Hoffmann, Jobst]

After switching to Emacs 31.0.50 I have a configuration problem (using
use-package:custom):

after 
,----[ C-h v TeX-style-private RET ]
| TeX-style-private is a variable defined in ‘tex.el’.
| Its value is ("home/???/.config/emacs/lisp/auctex/style")
| Original value was 
| ("/home/???/.config/emacs/auctex/style")
| 
| List of directories containing hand-generated AUCTeX style files.
|
|These correspond to the personal TeX macros.
|
|  You can customize this variable.
|
`----

This is what I expect.

But: If I create/open a LaTeX file containing 

\usepackage{blabla}

the file blabla.el isn't loaded though it exists in the above mentioned
directory. Is there something I'm missing?

Conversely: If I use the original value - see above - and move the .el-
files to /home/???/.config/emacs/auctex/style, loading .el-files  works
fine, but I would prefer the other directory structure.

Any hint is really appreciated!

Kind regards
Jobst