When to Use a Comma Before “Because”
Generally, there should not be a comma before because in a sentence; this
ensures that the cause-and-effect relationship between the dependent clause
introduced by because and the main clause remains grammatically clear.
Occasionally, a comma is necessary before because, especially after a
negative statement, to avoid ambiguity about what the because clause refers
to.
You can read a because sentence out loud to check whether a pause before
because improves clarity.
Because introduces a reason, so the phrase “the reason is because …” is
redundant and should be avoided.
Because has a straightforward job to do in the English language. It is a
subordinating conjunction that indicates a cause-and-effect relationship,
introducing dependent clauses that answer the question “Why?”
Most of the time, when the dependent clause that because introduces comes
after the independent clause in a sentence, no comma should be used before
because. However, exceptions can and should be made when the lack of a comma
could lead to misinterpretation.
Here, we'll explain when to use a comma before because and when to leave it
out.
https://www.grammarly.com/blog/punctuation-capitalization/comma-before-because/