Created attachment 140333 [details]
Demonstration of tab selection animation in Digital Clock applet getting stuck

SUMMARY
When switching between different tabs of the popup of Digital Clock applet, the underline animation sometimes gets stuck. See video recording for demonstration.

STEPS TO REPRODUCE
1. Add Digital Clock applet to a panel.
2. Click on the applet.
3. Switch between tabs "Days", "Month", "Years" while observing the line under the tab name.

OBSERVED RESULT
Sometimes (it's inconsistent) the underline animation doesn't finish and gets stuck in unfinished state.

EXPECTED RESULT
The underline animation finishes all the time.

SOFTWARE/OS VERSIONS
Operating System: KDE neon 5.22
KDE Plasma Version: 5.22.3
KDE Frameworks Version: 5.84.0
Qt Version: 5.15.3
Kernel Version: 5.8.0-63-generic (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz
Memory: 7.7 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics 620