background-color and backdrop-filter: blur() don't want to work together in Safari 18 on iphone

My <selection> contains css:

background-color: rgba(255, 255, 255, 0.2);
-webkit-backdrop-filter: blur(1px); /*For old safari versions*/
backdrop-filter: blur(1px);

and my <selection> block is full white, despite the fact that there is a color image in the background

but it safari 17 it work correctly. If I remove one thing from the code, either 'background-color' or 'backdrop-filter', then the block takes on a predictable form.

Is there a way to fix this? Or will have to wait until Apple fixes another problem in the Apple Web Kit?