Update blocks all over my World?

Hey!

So i bought a 300x series Gpu and wanted to try out RTX,

i bought the win 10 edition of minecraft and i converted my java world to bedrock.

Now it seems that there is a new block every where, which seems to fill up empty space under ground such as mines, caves etc...

I found out that its some kind of "reserved" block but no one seems to have found a solution for it, or maybe i've just been asking in the wrong forums.

Please, if you have any clue on how to delete this blocks.

HIT ME UP!!!