GAS, aarm64 support for LDR's <extend> to be a label

[yearswriter]

...
adr x20, co_st 
ldr x21, [x20, #co_xx] 
...
  .equ co_xx, 0
  .equ co_sp, 8
  .equ co_fp, 16
  .equ co_lr, 24
co_st:
 .xword 0xFC
 .xword 0xAE
 .xword 0xCB
 .xword 0xDF

Compiles and, at least afaik works as intended, on GNU assembler (GNU Binutils) 2.45.1 configured for a target of aarch64-linux-android, while lsp shows error index must be an integer in range [-256, 255]
_Although it is not really apparent that it should from ldr description in amd's or binutils documentation _
LDR <Wt>, [<Xn|SP>, (<Wm>|<Xm>){, <extend> {<amount>}}]

I was not sure how to formulate it, so sorry if I am wasting time. this is just a fun hobby for me.