Perhaps? He's had it for a while and it's kind of grown on him (not gotten larger, but kind of stayed in proportion with his tail). He doesn't get any discomfort it. I hope it is - he seems fine. I appreciate all the help everyone's given me on this. I'm going to keep taking pictures to track it just in case.
Update: I'm taking her to the vet (appointment set for thursday morning) as her breathing has become a bit crackly which I've seen can be signs of a respiratory infection. Hopefully vet will be able to tell me more and if she has a respiratory infection + more about the tail.
Took her to vet - she has a mild respiratory infection and was given antibiotics for it for 2 weeks and the tail is probably just an injury - said to keep an eye on it for shedding and stuff and apparently shes overweight to lmao I guess I'll have to feed her less. Thanks for everyone's help here, she's fine.