Do bonus action spells take spell slots?

You cannot cast Counterspell using a 1st or 2nd level spell slot, because it's a 3rd level spell What it's talking about is the spell you are *countering

The difference in average damage is just 3 damage, so it's not enough to justify the higher-level spell slot counter spells and to dispel magic

spell slot calculator As a rule, any spell of level 1 or higher uses an apposite spell slot , regardless of the casting time

spell slot calculator 5e slot count = GetActionCount Applies to spells that require reagents , items that stack , or items with charges ; used in the default UI to display