Hi. They both have similar meanings. It just depends on the situation. “Something is a problem to me” meaning it’s something you have an issue with, something you do not approve of. “Something is a problem for me” Meaning is something you struggle with, like riding a bike or speaking around large crowds. You can say “Speaking in large crowds is a problem for me”. They both have similar meanings, with slight differences. Hope I can help 🙂.

I believe that it is just a matter of preference. I have heard it used in either form frequently. In my part of England it is likely that 'a problem for me' would the most common.

Hi Jordi, I'm a native British English speaker. Both sound fine to me, but the nuance is different. "Something is a problem for me" sounds a bit more emotional and less literal, as it is more indirect. For example, "it is a problem for me that you always arrive late" (i.e. it makes me feel bad), whereas "to me" sounds like the thing itself is directly, and perhaps physically affecting the subject, e.g. "The lack of recycling facilities in this city are a big problem to me". It sounds a bit like one is saying "in my opinion" in this case. Hope this helps!