Manager’s handling of the account “Tax payable” has recently changed. From Releases page
09 Dec 2019 Fixed tax payable starting balance issue by converting it from built-in account into regular account (see topic) 19.11.85
In the past it was a special system account automatically created when a tax code was used, and the default account in all tax codes unless a specific account was selected by the user. Now “Tax payable” is an ordinary account (which can be deleted or renamed if present at all in a COA), and all tax codes default to “Suspense account” unless explicitly set to a specific account.
The Tax code guide has been updated to reflect this change and if Managers version update code does not automatically implement the conversion you will need to manually configure the account used by each of your tax codes, see the updated guide on tax codes for details.