AP 5.5.0 Win11 - Bug with __regular__ being added to columns when missing

Since upgrading from 5.4.4 to 5.5.0 I’ve noticed that when a column name is changed downstream, if the Joiner node (and maybe others?) uses that column for the matching criterion, then it shows the missing column as:

(MISSING) _regular_ColumnName (where ColumnName is the missing column)

I’d expect to see:

(MISSING) ColumnName

I don’t know why it has prepended it with regular - that’s not something that exists in my workflow.