UPF is not inherently bad. Some UPFs (Pasta, wholemeal bread, baked beans, probiotic yoghurts, wheat biscuit cereals), are actually good for you.
The problem is that UPFs come from manufacturers who are trying to get you to buy more of their product, by playing tricks with the brain's response to it.
There are food labs where people are having their brain scanned while they sip different soda formulations, tobacco companies buying food companies to apply their research methodologies, and people figuring out packaging noises and shapes in order to make your old/slow brain excited at the crap you're about to eat (the pringles can is hard to use on purpose, for example). This is all symptomatic of a global food industry that needs you to buy more food, so needs you to consume more food, regardless of nutritional impact.
I recommend reading Chris van Tulleken's book and watching (if you can) the documentaries he made on the subject.
Yes, the Brazilian paper that started all this said "UPF is harming the health of the nation", but the root cause was not UPF processes, it was food industry processes that often require them to produce UPF.
It isn't the UP that makes the F bad, it's that some profitable but bad F needs UP to be viable.
It is therefore perfectly possible for meat substitutes to be UPF and healthy, just as some other UPFs are healthy. In fact, arguably they need to be both to survive.