וְאֶת־מַתְכֹּ֨נֶת הַלְּבֵנִ֜ים אֲשֶׁ֣ר הֵם֩ עֹשִׂ֨ים תְּמ֤וֹל שִׁלְשֹׁם֙ תָּשִׂ֣ימוּ עֲלֵיהֶ֔ם לֹ֥א תִגְרְע֖וּ מִמֶּ֑נּוּ כִּֽי־נִרְפִּ֣ים הֵ֔ם עַל־כֵּ֗ן הֵ֤ם צֹֽעֲקִים֙ לֵאמֹ֔ר נֵלְכָ֖ה נִזְבְּחָ֥ה לֵאלֹהֵֽינוּ׃
Die Anzahl Ziegel hingegen, die sie bisher gemacht, legt ihr ihnen auch jetzt auf, ihr sollt nichts davon abziehen; denn schlaff angehalten werden sie, daher schreien sie und sprechen: Wir müssen gehen und opfern unserm Gott.
Rashi on Exodus
ואת מתכנת הלבנים means the total number of bricks which each made per day when straw was being supplied to them — that total you shall impose upon them now also, in order that the service may be hard upon them.
Rashbam on Exodus
מתכנת, the quota.כי נרפים הם, they are therefore able to make more of these bricks daily.
Or HaChaim on Exodus
כי נרפים הם, "for they are lazy!" Who had ever suggested that the idea to sacrifice to their G'd originated in the relatively light burden of work that Pharaoh had imposed on the Israelites up until then? Perhaps what Pharaoh meant was that the Israelites felt that now that Moses had arrived their lot would become easier and that therefore they wanted to thank their G'd for that by offering up thanksgiving sacrifices so that He would cancel out the servitude altogether. Pharaoh countered this euphoria by making the workload heavier so that they would not even entertain any idea of their servitude being near an end, i.e. those lies that Moses had fed them.