Launcher Error 400

On MacOS Sequoia (15.6.1) the Launcher (3.23.34-2.3.2) starts up. But logging in repeatedly is impossible. While 2 weeks ago it worked fine. A black screen with a text to retry with a different device or authentication method appears. It appears to be a so called Error 400.

1. Different device, ie., a second Mac also with Mac OS Sequoia does not work.

2. O​ther authentication methods do not work.

3. Clearing the caches does not work.

4. Restarting the router and wifi does not work.

5. Restarting the Macs does not work.

6. Reinstalling Launcher does not work.

7. However, logging in on an Android (15) tablet is successful. This is evidently is a Bedrock edition.

8. Logging in on the Minecraft website is successful.

Please advise.