Prints collapse on 3D benchy deck

Hi, I am new to 3D printing, I recently bought an Ender 5 plus for my first printer with a sonic pad, I installed the black PLA filament they sent with it, did a couple of very small solid prints & no problems. I then did the all in one test print, but reduced by 75%, with it being black it was hard to see, so I changed to an alloy coloured filament, it would only print up to the bridges then the print would start to collapse, before long it was trying to print in mid air. I have looked into a lot of YT videos & following their settings I have adjusted the extruded feed rate, leveled the bed, done & saved a bed mesh etc, I changed to the white filament supplied by Creality & it printed poorly, would not stick together and had a fluffy texture, so I went back to the ally filament, it printed well on the 3D benchy, until it got to the point of starting the deck & islands, then it seems to start not sticking the layers or missing layers & looks collapsed.

What am I doing wrong?

Hi there,

Would you happen to have any pictures of the failed prints that you could upload for us to take a look at?