Rhythm is hard, at least for me. And it's one of the foundational aspects of jazz. Jens Larsen, a jazz guitarist who has a bunch of really good YouTube videos on learning jazz likes to repeat ad naseum that "it's not about the notes, it's about the way you play them." He's right, and by "the way you play them" he means rhythm (and phrasing more broadly).
I've been avoiding working on rhythm in my practice because I know it's difficult and going to feel like I'm getting nowhere for a while. But I finally cracked that today and started digging in. I'm starting by just taking some short rhythmic ideas I've gotten from solos I've transcribed and reducing them to their base by only playing them with one note. Then I gradually add in other note options so I can see how the rhythm sounds with different melodic overlays. Once I've done this with 2-3 different short rhythms I then practice improvising using them. Slowly, painfully slowly, it gets embedded and I can play them more freely and my mind frees up to think less about the rhythm and more about the overlay.
Even though it's difficult, I already noticed a big improvement in just the session today. Not only does my playing sound more like "jazz" but it sounds clearer (i.e. more intentional) and I'm naturally taking more space as I play, which makes the whole thing sound more coherent.