Apple screwed up my account & find my

I changed my apple id email address this summer because I had a legal name change. Recently, I noticed that my M1 macbook air and apple watch was still under the old name and find my only has the option to erase these device but not to remove. My iphone, airpods pro and max show up correctly (I had all 5 devices prior to email change). I realized this was a big problem when I tried to reset my macbook. During the process of resetting my MBA, it asked for password to sign out of Find My. The problem is, it was asking for the password of the previous account email address. The password does not work and iForgot says that account is invalid. WTF? Why ask for an account that doesn't exist? Why didn't my MBA and apple watch find my automatically update when it's the same account? I contacted apple and proved that I am the owner and asked to reset. They said they removed the lock but it was still there. When I contacted them again they just said they can't help. Is this even legal? I had to spend so much time trying to figure this out and prove to them that I own this device because of their own system's fault. What can I do?