/usr/share/mozilla/extensions/ is in xul-ext-adblock-plus-element-hiding-helper 1.2.2-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/mozilla/extensions/{3550f703-e582-4d05-9a08-453d09bdfdc6}/
/usr/share/mozilla/extensions/{3550f703-e582-4d05-9a08-453d09bdfdc6}/elemhidehelper@adblockplus.org
/usr/share/mozilla/extensions/{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}/
/usr/share/mozilla/extensions/{92650c4d-4b8e-4d2a-b7eb-24ecf4f6b63a}/elemhidehelper@adblockplus.org
/usr/share/mozilla/extensions/{a79fe89b-6662-4ff4-8e88-09950ad4dfde}/
/usr/share/mozilla/extensions/{a79fe89b-6662-4ff4-8e88-09950ad4dfde}/elemhidehelper@adblockplus.org
/usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/
/usr/share/mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}/elemhidehelper@adblockplus.org