וַיְמָרְר֨וּ אֶת־חַיֵּיהֶ֜ם בַּעֲבֹדָ֣ה קָשָׁ֗ה בְּחֹ֙מֶר֙ וּבִלְבֵנִ֔ים וּבְכָל־עֲבֹדָ֖ה בַּשָּׂדֶ֑ה אֵ֚ת כָּל־עֲבֹ֣דָתָ֔ם אֲשֶׁר־עָבְד֥וּ בָהֶ֖ם בְּפָֽרֶךְ׃
און זײ האָבן פֿאַרביטערט זײער לעבן מיט שװערער אַרבעט, בײַ לײם און בײַ ציגל, און בײַ אַלערלײ אַרבעט אין פֿעלד; אַלדי אַרבעט זײערע װאָס זײ האָבן מיט זײ געאַרבעט, איז געװען מיט האַרטיקײט.
Sforno
וימררו את חייהם, they ruined their own lives not only by improper deeds, but also by succumbing to alien philosophies. This is described in Ezekiel 20,8 “and they rebelled against Me and did not want to listen to Me. No Man!- the idols of their eyes they did not cast out and the idols of Egypt, they did not forsake.”
Or HaChaim
וימררו את חייהם, They made their lives bitter, etc. The Torah speaks of עבודה קשה, to describe work which was very difficult by its very nature without it being performed under intolerable conditions. What was the nature of this work? The making of clay bricks or working in the fields.