I have a theroy.
I think that Rani and Baliyo might be lion hybrids and here is why.

While hybirds of the two in the wild are not a thing (due to location) in the lion guard we are shown that african lions can meet up with other type, it is not said if rani and co are other types of lions but i belive they are.

I belive that Janna, Surak and Sahasi are all Asiatic lions
frist let me tell you the diffreances between african and asiatic lions

Asiatic lions are smaller then african,The males mane tends to be darker and shorter then african making the asiatic lions ears more visable and they have a 'skin fold on there bellys.

Size

size is a hard one to show due to Simba and Surak not shareing time next to each other but with the magic of editing (and fuli being a main character) we can get them to be

While surak is a little bit father back it is clear he is a bit smaller then Simba, you can also see baliyo is almost the same size as surak evan though he is younger (we will bring this up later)

Darker

well the night pride is darker then most pridelanders so we will need to compare them to the darker pridelanders aka kovu and scar, we will be using there LG designs for this.

As you can see kovu and scar have more redish hues to there coat while Surak hasnt, this could be the diffrance between the two lions.

Ears

the question is are Surak and his brothers ears more visable

i think its safe to say yes , when comparing them to the other males we see such as scar,Simba,Kovu and scars guard boths ears apper infront of the manes (ignoring the forlock)

Now that we have looked into that we can go into more detail why i think rani and Baliyo are hybrids and not asiatic lions them selves, Hybrid AfricanXasiatic lions are often born with defects and health issues, This describes what im seeing with the two Bailyo is the stand out being pidegon toes

Ranis defect is a little harder to see, as she uses kiaras character model sometimes (with the head changed) it dosnt show all the time , Rani as far as i can tell is roach backed or what ever it would be called in a lion (its roach back in horses), It can be genetic and also be hard to spot (ranis is only 'light' and could be far worse)

as you can see ranis back is curved from her shoulders while other lions backs dip after the sholders before riseing neat where the hind legs are,

These defects and the face Baliyo is as big as surak despite being younger makes me think they are hybrids , as baliyo could get his hight from his african parent. In looking things but as far as i can tell hybrid lions can breed to pure african lions so your ships are safe .

Big thankyou to happystool for leting me throw my thoughts at her and helping me with some of the reserch