If this isn't a targetted advert in my browser, I don't know what is.
And here's where you turn it off:
I tell people Waterfox if you just want Firefox without the bullshit.
LibreWolf if you're more hardcore about privacy and are willing to deal with the occasional site not working.
I have both installed but mainly use LibreWolf. I have Waterfox for "irl stuff" like banking/shopping, etc stuff that doesn't approve of VPN use and I have to enter my real details into anyway.