No, once a given checkpoint is made it's completely static. Even the problem of AI generated material being used as training data for subsequent checkpoints is overblown: uncurated and incorrectly tagged it's the same as mixing in bad data of any source, but you've got a bunch of hobbyists making LoRAs or finetuning checkpoints using hand-curated AI images that meet whatever criteria they set (like what I mentioned about the models can effectively synthesize new things by combining concepts with mixed success? Some people, particularly fetishists, basically try to make a LoRA or something that reinforces the cases of a model getting the concept right because they don't have a lot of separate art). I've also seen an example of someone actively trying to make a LoRA that was as messed up and full of common AI defects as possible to be used with a negative weight to drive the output away from those concepts.