Sorry, this confused me a bit. Are you saying you are painting your room, and just going to paint over the wallpaper?

If the wall the paper is on is just plaster that's still nice and smooth then it's best you just take the paper off then paint. It will also give it a better look that way as the paper might show through. Especially if it's bubbling. Unless the paper is new then just prick the bubbles and release the air, if it's old then it's most likely started to decay and will come on at some point anyway.

You might need some stronger paste so it sticks to the wall too if it doesn't want to stick

maybe try a heat gun and push it back down when it is warm

u0001f602 wrote maybe try a heat gun and push it back down when it is warm

I dont think this would work as paste isnt a addheasive like a sticker

Different idea!
If you have a needle & syringe, you can put some glue in the syringe. Then put some glue behind that bubble and stick it back down.

Take a clothing iron and iron it back down. If that doesn't work then you'll have to take a knife an slice a hole the length of the bubble and put a lift adhesive (not glue, something like spray 90 in a non spray form), paint it on the wall and stick the paper back down. The issue you'll run into is that it will be very hard to get it flat as it would be hard to keep pressure on it for a long period of time and most glue / adhesive is water base. Water makes paper shrivel.