Created attachment 153370 [details]
From top to bottom: Timer icon button, Timer remaining time in sec, (kimpanel (just to show the boundary))

SUMMARY
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On a vertical panel the timer displays a very large button and lost the ability to change time by units larger than seconds without clicking.

STEPS TO REPRODUCE
1. Put a timer on a vertical panel.

OBSERVED RESULT
See the screenshot.

EXPECTED RESULT
The timer remaining time should be displayed as HH:MM:SS, and takes the (vertical) place of only one line of text (Same as the digital clock!). Scrolling on the digits should change the corresponding digits I am hovering. 

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: 5.18.2-gentoo-x86_64 / 5.26.2
(available in About System)
KDE Plasma Version: 5.26.2
KDE Frameworks Version: 5.99.0
Qt Version: 5.15.5

ADDITIONAL INFORMATION
https://invent.kde.org/plasma/kdeplasma-addons/-/commit/ba011368af76abc1abbacab1ccce8075e45a6ae1 seems to not only be unable to fix the problem that it takes too much vertical space, but has also *degraded the usability* of the timer.