This happened to me after I had kids! Suddenly jeans that fit me were sliding off my butt whenever I bent down, sat, squatted to help a toddler....somehow my body changed just enough or something....
Anyway. It's not about the jeans. It's about wearing a belt. I can still wear flattering cool jeans, NEVER MOM JEANS, from American Eagle (cheap way to get different silhouettes with flattering butt), or Gap 1969 or any of the more expensive designer jeans, INCLUDING lower rises, as long as I wear a belt so they don't ride down my butt when I bend over. And of course some higher rise jeans are cool, every brand offers a few. But a belt will stop your butt crack issue in any style :)
It's weird, because I never used to have to wear a belt other than for decoration, but now it actually serves a purpose.