The Ubuntu package for weewx 5.0.1-3 installs a ton of stuff, including the skins data, in /usr/share/weewx.
/etc/weewx/skins contains three empty folders: font, lang, and NOAA.
I copied /usr/shared/weewx/weewx_data/skins to /etc/weewx/skins and veriified that Seasons/skin.conf is there. I restarted weewxk and it still claims that it can't read Seasons/skin.conf.
philbert@inspiron:~$ ll /etc/weewx/skins/Seasons/skin.conf
-rw-r--r-- 1 weewx weewx 27403 Feb 4 18:48 /etc/weewx/skins/Seasons/skin.conf
philbert@inspiron:~$ ll /etc/weewx/skins/Seasons/lang/en.conf
-rw-r--r-- 1 weewx weewx 9459 Feb 4 18:48 /etc/weewx/skins/Seasons/lang/en.conf
philbert@inspiron:~$
Feb 06 14:15:15 inspiron weewxd[700]: INFO weewx.manager: Added record 2024-02-06 14:15:00 PST (1707257700) to database 'weewx.sdb'
Feb 06 14:15:15 inspiron weewxd[700]: INFO weewx.manager: Added record 2024-02-06 14:15:00 PST (1707257700) to daily summary in 'weewx.sdb'
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: Running reports for latest time in the database.
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: Running report 'SeasonsReport'
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: Cannot read skin configuration file /etc/weewx/skins/Seasons/skin.conf for report 'SeasonsReport': Config file not found: "/etc/weewx/skins/Seasons/skin.conf".
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: Cannot read localization file /etc/weewx/skins/Seasons/lang/en.conf for report 'SeasonsReport': Config file not found: "/etc/weewx/skins/Seasons/lang/en.conf".
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: **** Using defaults instead.
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: Running generators for report 'SeasonsReport' in directory '/etc/weewx/skins/Seasons'
Feb 06 14:15:15 inspiron weewxd[700]: DEBUG weewx.reportengine: No generators specified for report 'SeasonsReport'