1) Paste text with format into writer.
2) Undo with ctrl-Z
3) type or paste new text.
This text has the format of the pasted text that was "undone".
Possibly because the current text format, changed by the formatted paste, does not get "undone" when the text is rolled back. This doesn't happen at the beginning of a line, only when the cursor has text to its left.
Duplicate of 36958.
Although they describe it slightly differently, it's the same root cause and issue.
*** This bug has been marked as a duplicate of bug 36958 ***