Had similar problems here with the KDE/Plasma Software Updates widget. It never respected my »weekly« setting. Last year, I deactivated it.
I now use mostly YaST’s excellent »Online Update« and »Software Management« for keeping my Leap 15.0 main rig up to date and check for any package dependencies.
Since I work within xterm+bash a lot every day, I manually use the zypper command near weekends in order to look for any updates:
rig:~ ▶ **zypper lifecycle**
Product end of support
Codestream: openSUSE Leap 15 2021-11-30
openSUSE Leap 15.0 2019-11-30
Package end of support if different from product:
libIlmImf-2_2-23 Now, installed 2.2.1-lp150.2.6.1, update available 2.2.1-lp150.2.9.1
libapparmor1 Now, installed 2.12.2-lp150.6.14.1, update available 2.12.3-lp150.6.17.1
libopenssl1_0_0 Now, installed 1.0.2p-lp150.2.13.1, update available 1.0.2p-lp150.2.16.1
libopenssl1_0_0-steam Now, installed 1.0.2p-lp150.2.9.1, update available 1.0.2p-lp150.2.16.1
libopenssl1_0_0-steam-32bit Now, installed 1.0.2p-lp150.2.9.1, update available 1.0.2p-lp150.2.16.1
libsolv-tools Now, installed 0.6.35-lp150.2.3.1, update available 0.7.5-lp150.7.1
libwps-0_4-4 Now, installed 0.4.9-lp150.2.3.1, update available 0.4.10-lp150.7.1
libxml2-2 Now, installed 2.9.7-lp150.2.6.1, update available 2.9.7-lp150.2.10.1
libxml2-2-32bit Now, installed 2.9.7-lp150.2.6.1, update available 2.9.7-lp150.2.10.1
libxml2-devel Now, installed 2.9.7-lp150.2.6.1, update available 2.9.7-lp150.2.10.1
libxml2-tools Now, installed 2.9.7-lp150.2.6.1, update available 2.9.7-lp150.2.10.1
libyui-ncurses-pkg8 Now, installed 2.48.5.2-lp150.2.3.1, update available 2.48.5.2-lp150.7.1
libyui-qt-pkg8 Now, installed 2.45.15.2-lp150.2.3.1, update available 2.45.15.2-lp150.7.1
libzstd1 Now, installed 1.3.4-lp150.1.2, update available 1.4.2-lp150.2.3.1 2019-11-30
libzypp Now, installed 17.7.2-lp150.2.9.1, update available 17.12.0-lp150.2.13.1
nvidia-computeG04 Now, installed 390.116-lp150.7.1, update available 390.129-lp150.6.1
nvidia-gfxG04-kmp-default Now, installed 390.116_k4.12.14_lp150.11-lp150.7.1, update available 390.129_k4.12.14_lp150.11-lp150.6.1
nvidia-glG04 Now, installed 390.116-lp150.7.1, update available 390.129-lp150.6.1
polkit-default-privs Now, installed 13.2-lp150.8.22.1, update available 13.2-lp150.8.25.1
python-solv Now, installed 0.6.35-lp150.2.3.1, update available 0.7.5-lp150.7.1
x11-video-nvidiaG04 Now, installed 390.116-lp150.7.1, update available 390.129-lp150.6.1
yast2-pkg-bindings Now, installed 4.0.13-lp150.2.10.1, update available 4.0.13-lp150.2.13.1
zypper Now, installed 1.14.12-lp150.2.9.2, update available 1.14.28-lp150.2.13.1
zypper-aptitude Now, installed 1.14.12-lp150.2.9.2, update available 1.14.28-lp150.2.13.1
zypper-log Now, installed 1.14.12-lp150.2.9.2, update available 1.14.28-lp150.2.13.1
rig:~ ▶ _
Oh, time to update some packages.
Sorry, all I can offer is this workaround, not a solution. Oh well.