I fully subscribe to the idea that the TikTok theory is bullshit in an analysis-of-the-literature sense.
However, as someone who has witnessed strong evidence of lion cannibalism I feel compelled to note that lions do eat each other, and it is not necessarily due to extreme circumstances.
In the case I saw a female with a prior injury (probably making it difficult for her to keep up with other members of her group) that was likely killed by three older males who were not part of a pride. They had eaten the hindparts and viscera of the female and were resting under a tree about a quarter mile away, with their faces covered with blood and with distended bellies. Pretty strong evidence.
So, in the Lion King story, do we have evidence that the authors imagined Scar ate Mufasa? Not really. But can and do lions kill and eat other lions? Absolutely.