I’ve had a similar experience. I learned some French in school years ago, and much later picked up a bit of Spanish on my own. Even knowing they’re both Romance languages, they just feel very different when you hear them. With Spanish or Italian I often feel I can guess words from context or sound alone, but with French everything seems more compressed and connected, especially in fast speech.
I don’t think it’s a bad thing, just different. When I started listening to other varieties of French (like Swiss or Canadian French), it made me realize how much history and pronunciation changes shape how a language sounds today. So I get why French stands out to people, even within the same language family.