According to Chrome Enterprise policy list, Google has renamed the URLBlacklist and URLWhitelist configurations on Chrome version 86 as URLBlocklist and URLAllowlist.
What impact this has?
If you have defined URL blacklist or whitelist configurations for the managed Chrome app on your Miradore site, they will not work on Chrome apps which are of version 86 or above. The URL restrictions will still work on previous Chrome versions though.
What should I do?
The Google documentation also provides very clear examples for defining the URL filters.