Ok, now I lost you.
A L2 bridge between wifi and ethernet Is the most common setting/setup.
The problem is L2 bridge over wifi.
Search for posts by bpwl with the keyword "4 address" and/or "pseudobridge" he often explained how the station, station pseudobridge, etc. work, they may help you understand the matter.
You will find that in your case there Is a workaround (or a "crutch" as someone defined It) consisting in putting the bridges on both sides into a tunnel (like EOIP), example: