If it’s just started check the pipes for splits from the turbo to the intercooler and intercooler to manifold. Pipes can have temporary repairs done with duct tape and a zip ties. The intercooler may damaged and easier to swap out than repair.
Before assuming its the turbo (it could be!) – see if there are any breathers that are blocked. I had this on an X5 and feared the worst – turned out to be an easy and cheap fix – £100 for the breather / diagnosis and fitting!
It’s a Peugeot Partner and it’s been doing it a while now, but is definitely getting worse.
Not sure about a drop in power as I have to drive it like an old granddad to stop it belching smoke over all the other road users.
Thanks for the advice. Will try and see if anything else is blocked before presuming the worst.