Hi.
You can use A13, no need to downgrade.
There is a long thread about this here: Android 13 and SailfishOS on Xperia 10 III
TLDR is:
You can use A12 or A13, but download the binaries that the documentation says:
Software binaries for AOSP Android 11.0 – Kernel 4.19 – Lena (latest)
EDIT:
Corrected the img file