This seems to have been fixed in 7.1 since:
https://git.libreoffice.org/core/+/937b780e3f696552fc686bf0c80c3050443b111a
author Martin van Zijl <email address hidden> Wed May 27 08:21:39 2020 +1200 committer Heiko Tietze <email address hidden> Tue Sep 15 08:40:04 2020 +0200
tdf#76898 standard filter: add buttons to remove conditions
This seems to have been fixed in 7.1 since:
https:/ /git.libreoffic e.org/core/ +/937b780e3f696 552fc686bf0c80c 3050443b111a
author Martin van Zijl <email address hidden> Wed May 27 08:21:39 2020 +1200
committer Heiko Tietze <email address hidden> Tue Sep 15 08:40:04 2020 +0200
tdf#76898 standard filter: add buttons to remove conditions