A close-up of one spot can show its shape but not how a problem is developing. Photograph the whole tree philodendron, then the affected leaves, including their undersides.
Record whether the marks are on old foliage, new foliage or both. Note whether they began after a move, a cold period, a spray or a change in watering.
Separate observation from a disease name
Several causes can produce marks on leaves. Do not label a problem anthracnose, mites or nutrient deficiency solely because one online image looks similar.
Inspect for visible insects, webbing, residue and soft tissue. Check the root environment and whether foliage is repeatedly staying wet. Keep affected plants accessible and avoid moving damaged leaves through a crowded collection unnecessarily.
Date the photographs and compare the same areas later. Old spots may remain after the cause has been addressed, so new damage and new growth deserve particular attention. If you seek a diagnosis, include the plant's name, the growing medium and the treatment history. That information helps turn a photograph into a usable case rather than a guessing exercise.
The RHS leaf-damage guide distinguishes several possible causes of spots, browning and yellowing. Photographs and a care history provide context for diagnosis; colour or one matching internet image is not enough to name the cause.
Related reading: Tree Philodendron Problems: Leaf Spots, Mites and Scale.