First.
Modern stealth missiles are more of low observable/quasi stealth missiles than actual "stealth" missiles, as in as stealthy or more stealthy than stealth fighter jets.
They mainly rely on their stealth shaping, and while they do have composite and ram, but its more similar to ram and composite applied on fighters like tejas, gripen, su35, rafale etc, they don't have stealth fighter level RAM/RAS.
For example Tomahawk missiles is considered to have rcs of 0.3-0.5m2,
while Storm shadow/scalp is considered to have rcs Of 0.01-0.03m2.
That is 15 to 30 times smaller rcs than Tomahawk, that will decrease the detection and tracking range of storm shadow/scalp by 1.5 to 3 times compared to tomahawk.
A major difference but not as game changing of a difference as found between 4th and 5th gen fighter jet airframes.
Modern large ground based aesa radars can still detect rcs as low as 0.01-0.03m2 at BVR ranges, I.e. 60-90km range. and track it at 40-70km range, though limited by line of sight so depends on altitude of the targer too.
Obviously it can detect and track large 0.3-0.5m2 target at even longer ranges given it has line of sight for that.
And L and VHF can detect at lot longer ranges, but again dependent on target's altitude due to limited by earth's curvature.
now, most cruise missiles follow horizon mapping and in later parts of their flight as they get close to the tathet,follow follow terrain mapping to stay below radars field of view by taking advantage of earth's curvature.
In some missions they fly entirely in terrain mapping modern sacrificing range.
A ground based radar due to earth's horizon is limited In its field of view.
So for a missile doing terrain mapping/sea skimming radar will only get a line of sight at 30-60km, depending on how high the ground radar is and how close to water/surface missile is flying.
So as the radar gets line of sight it will be able to detect both tomahawk and storm shadow, and storm shadow in this particular case doesn't provide significant/large enough delay in detection, as terrain mapping becomes a bigger limit in detection than rcs, in this specific case.
But again, even in this case the low rcs shaping of stormshadow will provide some benifits, but its nowhere near game changing level benifit that makes cylindrical shape tomahawk obsolete compared to stealthy stormshadow.
Stealth shaping of cruise missiles provides lot more benefit when aerial detection elements like awacs and even fighter jets are present in air, in this scenerio they provide quite significant benifit, though it is case by case dependent.
So stealth shaping provides significant benifits, but it doesn't make cylindrical shaped cruise missiles obsolete or out of their league.
Like the latest block V tomahawk missile entered service with US military in 2021 and retained its cylindrical shape, even though America's first low rcs shaping cruise missile The AGM-129A Advanced Cruise Missile (ACM) entered service with the US Air Force in mid-1990s
I would also like to add, while stealth shaping is worth it, but it does not make subsonic low rcs shaping missiles like stormshadow better than brahmos.
Both are different missile with each having their own place.
At close ranges, more EO and IR sights have improved a lot, so even if these missiles were as stealthy as stealthy fighters, they will still be tracked and targeted at 30-50km by EO and IR methods, and engaging a subsonic missile at close distances and even point distances is a lot easier compared to engaging something like a brahmos coming at you at mach 2.8 or 2.8+ at close or point distances.
If a ~500km range storm shadow costed as much as a ~500km range brahmos, then I would prefer to have brahmos than stormshadow, even if multiple stormshadows can be carried by a fighter jet compared to single brahmos.
But it doesn't, a storm shadow cost 3-4 times less than a single brahmos, and you can carry multiple of it, that's why it has its own place.
And we do already use storm shadow/scalp on our rafales.
And are developing our own next gen autonomous subsonic cruise missile/drone that will also feature stealth shaping called cats hunter.