This looks like a type of environmental injury on the tomato foliage. For example, challenging spring weather conditions - cool temperatures, wind, cool, wet soils, etc. We have received several questions and photos about this. 

These are warm season plants that grow best in warm temperatures and soils. Plants tend to grow out of it if not affected by further stressors. No treatment is necessary.  https://extension.umd.edu/resource/vegetable-seedlings-or-transplant-leaves-yellowing-turning-white-or-are-spotted-or-scorched

Here is more information on growing vegetables in containers https://extension.umd.edu/resource/growing-vegetables-containers

Marian

You are welcome.

Marian