As somebody who used to be a bit of compulsive shopper, I sympathize. I think I've partly changed just because I've got older and am feeling the weight of all the 'stuff' more.
There are still some types of 'stuff' that I find really tempting. If it's online, I stick it in a basket and tell myself I'll wait until after the current credit card cycle is over, so it would be on next month's bill rather than this one; or if I see it in a shop, I'll take some pictures and tell myself if I still want it the day after I'll consider going back for it. I very seldom do!
I'd try reframing your thinking about advertising. Companies create advertising which tells us that buying Christmas pajamas, packet sauces, takeaway coffees, new sofas, new kitchens, new phones, TV subscriptions, software etc. will make us feel happier, more connected, more loved, more fulfilled, more entertained, less bored, more beautiful.
It's bullshit. These companies don't give a shit about us; they, and the media platforms that carry their advertising, just want to keep us spending. Watching people curate their filtered lives on Instagram is not informing us and developing our aspirations - it is very very fake and designed to part us from our attention/money/time.
Might it be helpful to start tracking your spending so you can quantify what you're spending the money on? I might suggest watching the first episode or two of the Rebel Finance School videos on Youtube. They are very cheesy but quite convincing in their opposition to stuff that we are told we 'should' want to buy. I found them quite inspiring in helping me want to save rather than buy.
These are just a few of the things that have worked for me. Good luck!