Glad to hear. I've also now had time to manually apply the patches and have not seen any issues so far! Thank you! If anything does turn up later down the road I'll let you know.

I apologize, you seem to be right. Even though the package build log shows that all patches were applied, it seems there are some hunks missing in the generated sources.
I've attached my patches, but those are most likely correct. There seems to be an issue with my distribution's package manager. I will investigate this and report back afterwards. Maybe I'll just build it manually.

I think that it means that you only applied the last two patches.

Thanks a lot for your cooperation.

Contrary to your expectations, all gpg --card-status fail after yubikey insertion:

In case you need any information, be sure to let me know. Maybe we can add some manual loggers to the patches, to confirm that everything is working as you imagine it to?

I'm certain I've applied the patches correctly. This is my current patchset:

I've uploaded the requested information with triple verbose and debug-all setting in the scdaemon.conf as scdaemon.log:

I've applied the linked patch, but still experience the error. Most of the times, I cannot access my yubikey at all and I am not sure what is blocking it.
I've tried to include as much debugging output as I could below. Please let me know if there is anything else I can do to debug this.

With the patch and after starting a new gpg-agent, gpg --card-status now works immediately.
But when I re-plug the yubikey, gpg reports gpg: OpenPGP card not available: Card error until either gpg-agent is restarted, or pcscd is restarted.
pcsc-lite in debug mode reports no errors, but one log is obviously much shorter as gpg fails early (I've attached both, same pcscd and gpg-agent instance).

I've applied the patch and can confirm that the segfault is fixed, but gpg still has severe problems communicating with the Yubikey over pcsc-lite.

I've taken the liberty to regenerate the valgrind report including libc and gnupg debugsyms. Maybe it'll help.

It segfaults on SERIALNO. Here's what valgrind outputs: