I decided to try the tabbed user interface.
I create a new text document, selected tabbed interface, LibreOffice crashed offering to recover "Untiled 1".
L.O. kept crashing until I managed to quickly change back to the standard interface.
Steps to Reproduce:
1. Create a new Writer document or open an existing Writer document
2. Select View > User Interface > Tabbed
LibreOffice stopped reponding.
Change to tabbed interface
User Profile Reset: No
OpenGL enabled: Yes
Tabbed inferface works with Calcs.
Build ID: 8061b3e9204bef6b321a21033174034a5e2ea88e
CPU threads: 4; OS: Mac OS X 10.15.6; UI render: default; VCL: osx
Locale: it-IT (en_IT.UTF-8); UI: en-US
Thanks for reporting this issue.
I believe this is a duplicate of bug 135495
In order to fix the issue, you can clean your user profile < https://wiki.documentfoundation.org/UserProfile >
*** This bug has been marked as a duplicate of bug 135495 ***