Q What’s causing blotched leaves on magnolia?

A I suspect this leaf is from evergreen Magnolia grandiflora, which needs a sunny, warm spot to thrive (so should have done well in 2020!) It’s natural for some leaves to drop in early summer as new growth emerges, but they should turn yellow first. The black spots suggest a lack of nutrients or waterlogged compost, so I suspect your plant is in a pot of multipurpose compost. Repot into John

Innes No3 this spring and ensure the pot drains well.