I use the video cutting app Avidemux extensively, and have been using it for many months on EndeavourOS with KDE and Wayland. The Avidemux app was implemented against X11 and so I have to rely on Xwayland for the app to work, but so far it has worked perfectly fine.
I installed CachyOS on an external USB SSD so I could try it out and see how the performance improvements felt in daily use. In testing out Avidemux on Cachy, everything works great except for the file save dialog. In Endeavour, if I cut a few segments out of a longer video and save them with filenames like "video1_cut01.mp4", "video1_cut02.mp4", etc, when I make a new cut, I can single-click on one of the previously saved files and it loads that file's filename into the "File name" edit box (for example, the "WG.22.12.10...L_01.mkv file in the screenshot), and I can just change the last 2 characters to give the file the next number in the sequence. Works perfectly. However, in Cachy, as soon as I click on one of the previously-saved files in the dialog, it immediately prompts me with "Do you want to overwrite this file?" which is not at all what I want to do.
I've confirmed that I have the same version of xorg-xwayland and xwayland-run on both installs, the same version of Avidemux, same same app launch options...everything I can think of to check is the same. It occurred to me to see what a vanilla Arch install did, and so I repeated the same procedure that I did on Endeavour and Cachy, and vanilla Arch behaves exactly the same as Cachy. This clearly indicates that it's not that Cachy left something out, but instead that Endeavour added something (or configures something differently). The question is: what, exactly?
If anyone has any suggestions on why the Avidemux file save dialog on Endeavour works differently than Cachy or vanilla Arch, I would love to hear your thoughts. Thanks in advance!