Plasma 5.24 featured options to set animation time for Desktop Grid and Slide effects. This is no longer available in Plasma 5.25. The default animation speed is fine for all other effects, but one might want to make those effects (related to window management) much quicker. Also the option for setting/removing margins between desktops in Desktop Grid effect is gone. SOFTWARE/OS VERSIONS Linux: Ubuntu 22.04 KDE Plasma Version: 5.25.5 KDE Frameworks Version: 5.95.0 Qt Version: 5.15.3
This was intentional, sorry. We've deliberately tried to move away from the ability to set individual animation durations, as it prevents the ability to globally set animation durations everywhere--including disabling all animations. And that's an accessibility feature (animations of any sort make people nausesous, so the ability to globally disable them all is important). If you think one of the effect's speeds is incorrect, feel free to file a new bug saying that.
"incorrect speed" is pretty much subjective... I think that would solve both issues: Restore the options to set the speed for certain effects as a *percent* of the default animation speed (defaulting to 100%). N% * 0ms is always 0ms, which solves your issue. There could probably be a 10% step for that value input. I didn't really like to use milliseconds to set those values anyway.
Heh, you're right of course. I should have said "If one of the effect's speeds doesn't feel right to you..." FWIW as of today, we've gone back to a 300ms animation duration for Overview, Desktop Grid, and Present Windows, which is what they were set to by default in Plasma 5.23 and earlier. As for the Slide effect, part of the problem seems to be that it's not respecting the global animation speed setting. For that, see Bug 450268.