Since installing the Mojave Security Update 2020-002 I do get a message that my Mac Mini 2018 was restarted because of a problem even I shut it down normally. The Mac Mini 2018 was running fine for 3 months. The Apple Hardware Check does not show any errors. Also tried to reset SMC and PRAM.
Is this a known bug? Just curios wether Mac mini 2018 users who also installed Apple's Security Update 2020-002 do see the same error message?
November 15th, 2020: I am pleased to confirm that BridgeOS firmware version 18.16.12561 fixes the Kernel panic bug_type 210 on a Mac mini 2018. Take a look at my answer.
October 19th, 2020: Apple released Security Update 2020-005 and macOS Supplemental Update. The bug has STILL NOT been fixed on macOS Mojave 10.4.6. On cold reboot "Your system was restarted because of a problem" message still shows up. I
July 16th, 2020: Apple released Security Update 2020-004. The bug has STILL NOT been fixed on macOS Mojave 10.4.6. On cold reboot "Your system was restarted because of a problem" message still shows up. No status update on Apple Bug Report. I am kind of surprise on how Apple seems to ignore Mac mini users. They messed up the T2 chip BridgeOS and simply don't care. I guess this bug will never be fixed. Users should rather invest in a new Mac mini model with their latests Apple processor. I am not willing to spent more money on any Mac mini.
Update May 28, 2020: Apple released Security Update 2020-003. However the bug has NOT been fixed on macOS Mojave 10.4.6. On cold reboot "Your system was restarted because of a problem" message still shows up. No status update on Apple Bug Report. Mac Mini users do not seem be relevant for Apple. Such a disappointment.
Update April 24, 2020: Workaround: Do not use Safari until Apple fixes the bug. Also make sure to set the default browser to Firefox, Chrome, Brave... which prevents opening Safari by accident. The shutdown message no longer shows upon a cold boot.
Update April 11, 2020: I did some further testing regarding my initial issue. I have restored from a previous system backup using SuperDuper. This backup clone does NOT include the Security Update 2020-002 Mojave and Safari 13.1. Surprisingly the shutdown message still shows up sporadically when I power on the Mac mini. I have completely shut down my Mac mini 2018 around 10 times. I have waited 5-10 minutes. 4 of 10 times the crash report showed up. It's really difficult to debug. What's interesting is the macOS Mojave Software Update does not show the Security Update 2020-002. So it seems to be already applied. I guess it is definitely related to the T2 BridgeOS Update or other firmware settings which have been patched during the Security Update 2020-002. Restoring from a 4 weeks old system backup does not resolved my issue.
This is a really bummer. I wish Apple would spend more time on testing. So far I haven't heard back from my Apple Bug Report #FB7646566.
Update April 2, 2020: I did a clean install macOS Mojave 10.14.6 without the Security Update 2020-002. As soon as I install the Security Update 2020-002 the annoying crash report shows up when the Mac mini has been shut down.
The Diagnostic Report reads as follows: {"caused_by":"bridgeos","macos_system_state":"shutdown","bug_type":"210","os_version":"Bridge OS 4.4 (17P4263)","timestamp":"2020-03-28 22:10:39.00 +0000","incident_id":"907CAD79-9364-4588-A25A-3810D0E72F8F"} { "build" : "Bridge OS 4.4 (17P4263)", "product" : "iBridge2,5", "kernel" : "Darwin Kernel Version 19.4.0: Mon Mar 2 20:38:56 PST 2020; root:xnu-6153.101.6~2/RELEASE_ARM64_T8010", "incident" : "907CAD79-9364-4588-A25A-3810D0E72F8F", "crashReporterKey" : "c0dec0dec0dec0dec0dec0dec0dec0dec0de0001"