On my iMac with MacOS 11.1 Big Sur, I was able to install and launch the MySQL Community Server 8.0.23 from mysql-8.0.23-macos10.15-x86_64.dmg without any issue.
I installed MySQL Workbench 8.0.23 from mysql-workbench-community-8.0.23-macos-x86_64.dmg, but was unable to open the app. The error box said “MySQL Workbench.app can’t be opened because Apple cannot check it for malicious software.”
Clicking OK did NOT provide me an option to grant an exception for a blocked app by clicking the Open Anyway button in the General pane of Security & Privacy preferences as Apple Support articles described. This button is supposed to appear and be available for about an hour after you try to open the blocked app. In my case, the button never appeared.
I attempted thru the Terminal to delete the quarantine with the commands xattr -d com.apple.quarantine <app-path> and sudo spctl —master-disable. This caused MySQLWorkbench to crash on opening, but I didn't get the warning box about malicious software. I reset things with the command sudo spctl —master-enable and removed the Workbench 8.0.23 app.
I saw a comment in the MySQL Forum https://forums.mysql.com/read.php?152,694334,694334#msg-694334
regarding Workbench 8.0.23 not opening on the new Mac M1, reporting that version 8.0.22 would run. My iMac is not of the M1 variety, but I downloaded and installed Workbench 8.0.22 from mysql-workbench-community-8.0.22-macos-x86_64.dmg.
After installation I started the Workbench 8.0.22 app, received the malicious software message, opened the General pane of Security & Privacy preferences, and was presented with an option to Open Anyway, exactly as described in the following Apple Support articles.