Immersion is immersion. Consuming any native content is almost always the best strategy. There are some pitfalls associated with reading manga, but they're not too significant. Still, I would rather immerse in anime as a beginner, with manga taking a secondary role.
Firstly, it's important to note that manga is not voiced, unlike anime. Consequently, often when reading you may get lost because you won't know how to say certain words correctly and with the right pitch accent. If you read something incorrectly, you may accidentally create a bad habit.
Since reading manga is reading immersion, it is crucial to balance reading with listening. Only through listening we can get exposure to native speech, get used to the sounds of the language and learn to understand speech without relying on textual cues.
You may not have access to high resolution scans. Reading text on low-resolution images can be frustrating, particularly when dealing with small text and complex kanji containing many strokes.
Lastly, setting up a sentence mining workflow for manga requires more steps compared to anime. You need to learn how to use OCR software, and how to connect it with Japanese dictionaries and Anki, which may be tedious for some people. OCR software often makes mistakes when recognizing text from images, and it can hinder your ability to quickly look up words. In contrast, when reading books or watching anime with TL subtitles you don't have to rely on OCR.