org.kde.plasma.libdiscover: Couldn't find a category for  "fwupd-backend"
file:///usr/lib/qt5/qml/org/kde/kirigami.2/private/PrivateActionToolButton.qml:74:5: QML Binding: Binding loop detected for property "value"
**
OSTree:ERROR:src/libostree/ostree-fetcher-curl.c:886:initiate_next_curl_request: assertion failed (rc == CURLM_OK): (1 == 0)
Bail out! OSTree:ERROR:src/libostree/ostree-fetcher-curl.c:886:initiate_next_curl_request: assertion failed (rc == CURLM_OK): (1 == 0)
29 -- exe=/usr/bin/plasma-discover
17 -- platform=wayland
24 -- appname=plasma-discover
17 -- apppath=/usr/bin
9 -- signal=6
11 -- pid=145522
18 -- appversion=5.24.5
21 -- programname=Discover
31 -- bugaddress=submit@bugs.kde.org
30 -- productname=discover/discover
12 -- startupid=0
KCrash: Application 'plasma-discover' crashing..

That doesn't look like a Plasma update issue, but rather Ostree 2022.03, can you try with previous Ostree in your pacman cache?

Down grading Ostree works OK here.

Rebuilds of Flatpak & Discover on new Ostree does not fix this.
Checking bug reports, just one so far for new Ostree, so not clear if this is KaOS only or upstream. I'll wait 24 hours for a solution, if not found, older Ostree will be build with epoch.

A bit of an update (and workaround).
Editing /var/lib/flatpak/repo/config to add http2=false fixes using Flatpak (thus Discover), so it is an issue with how ostree interacts with curl, similar issue https://bugzilla.redhat.com/show_bug.cgi?id=1697566

Installing curl 7.82.0, or building latest ostree on that curl made no difference,so I doubt this is a KaOS only issue.

EDIT:
Reverting one upstream commit fixes Ostree:
https://github.com/ostreedev/ostree/commit/4fd0d6b4c1566a75cb234a41e895a603c19448d4

Rebuild ostree is up in the build repo, please test:

sudo pacman -U http://kaosx.tk/repo/build/ostree-2022.3-3-x86_64.pkg.tar.zst