Yes, you cannot 1:1 migrate config. I think you have lantiq chip architecture.
lantiq devices got moved to DSA in v22.
The move to the DSA switch driver is a breaking change.
OpenWrt 22.03.0 first stable release -> More targets converted to DSA
You can do a manual config backup via Luci / System / Backup. Output is zipped readable config files.
You can open the created files in a text editor and use the content as hints to manually redo the config afterwards (but do not import the config set as is, as at least network config file has incompatible parameters). The switch ports wont work, if you do.