Totally normal! That's called tongue-thrust reflex and a lot of babies still have it at 6 months. Keep offering small amounts once a day, don't force it, and it usually fades within a couple weeks. Milk is still her main nutrition source right now anyway.
We went through this exact thing. What worked for us was switching from puree to letting her hold soft finger foods herself (baby-led weaning style) — she was way more interested when she controlled it. Try banana or steamed sweet potato strips.
If it goes on past 7-8 months or she seems to be losing weight, worth checking with your pediatrician just to rule out oral motor issues. But at 6 months with only one week of trying, honestly this sounds like completely typical adjustment.