Dolphin locks up on launch (rpm) or triggers mass Kioworker crashes (flatpak)

Fedora 43

Dolphin 25.12.0

For the last couple of months Ive found dolphin to be nigh unusable due to a long period of unresponsiveness, about 9-10 seconds, when launching the application. This lag occurs even without any drives mounted other than my base OS drive. And I think its related to whatever is causing kioworker to crash every second when trying to use the flatpak version of dolphin.

To be clear: I do not have any nfs or smb drives connected.

The above was generated by force closing dolphin while it was in the unresponsive state since it usually recovers after the 10 or so seconds. This even happens on a fresh user account without anything beyond the default files in its home folder.

This might be related to my kioworker crash but the stack trace on that is incredibly unhelpful. Ill still attach it here.

kioworker coredump
coredumpctl gdb -1 kioworker
           PID: 98574 (kioworker)
           UID: 1000 (arched)
           GID: 1000 (arched)
        Signal: 11 (SEGV)
     Timestamp: Sat 2025-12-13 13:30:40 EST (29min ago)
  Command Line: /usr/lib/x86_64-linux-gnu/libexec/kf6/kioworker /app/lib/plugins/kf6/kio/thumbnail.so thumbnail "" local:/run/user/1000/dolphinLAkwuC.12.kioworker.socket
    Executable: /usr/lib/x86_64-linux-gnu/libexec/kf6/kioworker
 Control Group: /user.slice/user-1000.slice/user@1000.service/app.slice/app-flatpak-org.kde.dolphin-3736278980.scope
          Unit: user@1000.service
     User Unit: app-flatpak-org.kde.dolphin-3736278980.scope
         Slice: user-1000.slice
     Owner UID: 1000 (arched)
       Boot ID: 98f862a7929943a38868d283bcd58630
    Machine ID: be8429389d654b1199a98220930549f5
      Hostname: arched-desktop
       Storage: /var/lib/systemd/coredump/core.kioworker.1000.98f862a7929943a38868d283bcd58630.98574.1765650640000000.zst (present)
  Size on Disk: 2.3M
       Message: Process 98574 (kioworker) of user 1000 dumped core.
                
                Stack trace of thread 71:
                #0  0x00007f8a12e3ab67 n/a (/usr/lib/x86_64-linux-gnu/codecs-extra/lib/libavcodec.so.61.19.101 + 0x23ab67)
                #1  0x00007f8a2c403e00 n/a (/app/lib/plugins/kf6/thumbcreator/ffmpegthumbs.so + 0xae00)
                #2  0x00007f8a2c404025 n/a (/app/lib/plugins/kf6/thumbcreator/ffmpegthumbs.so + 0xb025)
                #3  0x00007f8a2c406a70 n/a (/app/lib/plugins/kf6/thumbcreator/ffmpegthumbs.so + 0xda70)
                #4  0x00007f8a2c406d02 n/a (/app/lib/plugins/kf6/thumbcreator/ffmpegthumbs.so + 0xdd02)
                #5  0x00007f8a2c4014e3 n/a (/app/lib/plugins/kf6/thumbcreator/ffmpegthumbs.so + 0x84e3)
                #6  0x00007f8a31fb29f1 n/a (/app/lib/plugins/kf6/kio/thumbnail.so + 0xb9f1)
                #7  0x00007f8a31fb55b3 n/a (/app/lib/plugins/kf6/kio/thumbnail.so + 0xe5b3)
                #8  0x00007f8a31fb675d n/a (/app/lib/plugins/kf6/kio/thumbnail.so + 0xf75d)
                #9  0x00007f8a31fb808b n/a (/app/lib/plugins/kf6/kio/thumbnail.so + 0x1108b)
                #10 0x00007f8a3742e5a0 n/a (/usr/lib/x86_64-linux-gnu/libKF6KIOCore.so.6.20.0 + 0xac5a0)
                #11 0x00007f8a3742a372 n/a (/usr/lib/x86_64-linux-gnu/libKF6KIOCore.so.6.20.0 + 0xa8372)
                #12 0x00007f8a374282f6 n/a (/usr/lib/x86_64-linux-gnu/libKF6KIOCore.so.6.20.0 + 0xa62f6)
                #13 0x00007f8a31fb35f3 n/a (/app/lib/plugins/kf6/kio/thumbnail.so + 0xc5f3)
                #14 0x0000563e23ca9502 n/a (/usr/lib/x86_64-linux-gnu/libexec/kf6/kioworker + 0x1502)
                #15 0x00007f8a3662c975 n/a (/usr/lib/x86_64-linux-gnu/libc.so.6 + 0x2b975)
                #16 0x00007f8a3662ca28 n/a (/usr/lib/x86_64-linux-gnu/libc.so.6 + 0x2ba28)
                #17 0x0000563e23ca9895 n/a (/usr/lib/x86_64-linux-gnu/libexec/kf6/kioworker + 0x1895)
                ELF object binary architecture: AMD x86-64

While the flatpak discover is opened, this happens multiple times per second. I have not yet tested it in the fresh user account.

So the dolphin coredump is too large to fit in a post by about a thousand characters. If anyone has a suggestion on how to post it, I would love one.