Additional menu lines on document closing

After closing a document second (and more) main menu line(s) appears (see the screenshot below).
Steps to reproduce:
-start libre office
-install languagetool 4.4.1 or 4.5
-restart lo and press Writer document
-close this document
-second line appeared
-repeat press Writer document, close this document, one more line appears…
Tested on Linux Mint 19.1 and LO and LT 4.4.1-4.5

Same bug in LO and LT 4.6. Can developers explain why this weird bug has not yet been fixed? Thank you in advance.