My guy friend keeps putting me down?

I’ve recently started dating (after being quite closed off since a bad break up)
I’ve noticed my guy friend has been a bit negative about it, commenting on things about me that are red flags, saying it won’t work out etc. I think he’s joking…. But I’m not sure? I replied back and said well it’s a good thing you ain’t the one dating me then! And he said yes 100%.
urmmmm… any idea why he’s being a bit of an arsehole?
If it continues I’ll definitely bring it up

Updates
+1 y
Just to add - we’ve been good friends for like a year and a half, this is different behaviour really. He’s always been jokey but not sure about this one!
My guy friend keeps putting me down?
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