Google translation: "Quick collection does not work: shows crypric error message on MacOS Big Sur. When I highlight a picture and press keyboard B, an error message appears (see screenshot). Does anyone know any tip how I can fix this? Thank you in advance!"
See that bug report for simple workarounds. Please add your constructive opinion to the bug report, and be sure to click Like and Follow at the bottom of the first post. That will make it a little more likely that Adobe will prioritize a fix, and you'll be notified when the bug's status changes.
Adobe rarely discloses its plans, but I think it's pretty likely this bug will be fixed in the next release of LR. I and others posting on the bug report had been approached by Adobe to test out a new version that fixes the bug (I don't sign NDAs, so I don't have any confidential information to disclose, and I didn't participate in the testing).
Generally, there's a new release every two months, so we should expect the next one in a couple weeks.
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