Logon failed for login due to trigger execution / LOGON TRIGGER
The trigger is failing because the query that is used to set @Logon is returning more than one row.  Since @Logon is a varchar variable, an error occurs if anything more than one row is returned.

To test if the login is in the table, eliminate the @Logon parameter and use IF EXISTS to test if LoginName and the other criteria match a row in the table:

IF EXISTS (
    SELECT LoginName FROM [dba]..[MissusesAccounts_test]
    WHERE LoginName = @OriginalLogin
    AND LoginName NOT like '%WIN%' 
    AND ( @AppName LIKE '%Microsoft%' OR @AppName LIKE '%PowerShell%' ) 
    AND @ComputerName NOT LIKE '%sql%'
)


This is also safer from a logon trigger perspective because it always returns either true or false, so it will never cause an error (unless the MissusesAccounts table is dropped or modified).

You might also want to wrap this in some error handling so that if the MissusesAccounts or LogonAccounts_test table is accidentally dropped or modified, the error is handled, you are alerted, and it won't cause all logons to fail.