Foil is an ingenious storage device, culinary tool, and ad-hoc project utensil. Foil has its flaws.
Whirlpool says it may be tempting to place foil on the bottom of the oven to keep it clean, but doing so might harm the porcelain finish and heating components.
CNET agrees that foil isn't a good oven floor liner. This causes flame/heat source interference, lack of airflow, and heat reflection difficulties impacting food or the oven.
Some ovens may melt foils to the oven bottom, causing permanent damage and a costly repair or replacement.
CNET suggests using a cookie sheet, coated with foil or not, to absorb drips before they reach the oven floor.
There are heat-resistant and non-reflective silicone oven liners, but only for electric or convection ovens, not gas.