I’ve found that I had added Sensitivity Classification to all my Temporal Tables, (and only to some of my non-Temporal Tables).

As in 

    add SENSITIVITY CLASSIFICATION to dbo.Mytable.name with (LABEL = 'General', INFORMATION_TYPE = 'Public')

when I drop the Sensitivity Classification, the old error message is back.

I have an example that demonstrates the error:

    drop table if exists dbo.mytable
    go
    create table dbo.Mytable (i int not null identity(1,1) primary key clustered, name varchar(10) not null)
    go
    insert into dbo.Mytable ( name ) values ( 'abc' )
    go
    select * from dbo.Mytable where name = 1  -- programming error; data type mis-match

returns

    (1 row affected)
    Msg 245, Level 16, State 1, Line 8
    Conversion failed when converting the varchar value 'abc' to data type int.

This is the **correct** error message.
Now run this:

    add SENSITIVITY CLASSIFICATION to dbo.Mytable.name with (LABEL = 'General', INFORMATION_TYPE = 'Public')

and when you run this

    select * from dbo.Mytable where name = 1 -- programming error; data type mis-match

You will see this 

    Msg 245, Level 16, State 1, Line 169
    Conversion failed when converting the ****** value '******' to data type ******.

This is the **in-correct** error message.<br><br>
I've tried this code on Azure SQL Database where I get the in-correct message, and on SQL Server 2019 CU6, where I only get the correct message.<br><br>
I have reported this to Microsoft, and first-level support has acknowledged this looks weird, and that they will pass it on to their second-level support.