What if the opposite happens and "oh shit, all plastic in the world is getting eaten, it's worthless now!"

I’m afraid it will lead to a cessation of anti-pollution efforts

The bacteria release carbon during the decomposition process. So this isn't a "solution" in any meaningful respect. It's an instance of evolution at work, as a surplus resource becomes a food source for innovative organisms.

Also, we look at this as some kind of "clean-up". In reality, this is a threat to one of our most useful durable materials. It'll likely lead to the development of antiseptics to kill these bacteria colonies, as the last thing anyone with a hard plastic shell on their vehicle or appliance or equipment wants is a colony of plastic-eaters deteriorating it.

I dont really follow.

You think people are going to point to this as a reason not decarbon?

Im sure that idiots will, but those people were never going to make any meaningful effort to decarbon anyway.

Kind of, but there are plenty of paper and wood decomposers and we still use plenty of those. It will have consequences but you already have to service vehicles and you already need to sanitise hospital equipment

There are plenty of wood eating bacteria and fungus all around you and yet wooden buildings still exists.

These microorganisms need a favourable environment to start digesting wood, for example. That's why you can stack firewood outside without it being decomposed, but leave a tree out in the mud and it gets eaten.

There are exceptions, something like Serpula lacrymans, can bring down whole buildings, but even there the wood needs to be humid enough for it to be attacked by this fungus.

https://en.wikipedia.org/wiki/Serpula_lacrymans

To be fair, this has happened before, and I understand it was far hard for the bacteria then.

There was a time when cellulose could not be broken down. Trees fell and piled up for ... miles? Anyway, then bacteria figured out how to break it down. (We also got coal from the trees that were burred.) Anyway, we still build out of cellulose. Sometimes we treat the cellulose, sometimes we don't.

Plastic may, or may not, end up the same way.

I don't think bacteria can stop Big Oil from pumping oil to make plastic and Big Plastic from making consumer things.

When the plastic eating bacteria starts endangering the existence of artificial consciousness in the machine, life on earth will be purposefully wiped out.

Your results may vary.

Sure, but often plastic is used precisely because it doesn't rot when wet for extended periods.

To be fair, material scientists are redoing everything always as it is

Well, its possible that the mutations necessary were very close to something they already had. Or very 'lucky' mutations happened, interpret that as you will.