I'm not sure this is helpful but may clear up some doubts.
My Thai wife and I have been legally married for over 47 years.
Her Thai Birth Certificate shows her DOB as 1945, no Day, no Month.
Her Thai Passports over the decades simply show 1945.
When her first Thai digital PP was issued the DOB line shows XX XXX 1945 inline with International convention. Her latest Thai PP issued in 2022 shows the same.
She obtained her first UK PP over 40 years ago when the application was submitted ny snail mail. Faced with the DOB question, I wrote in 01 JAN 1945 because my own DOB is 31 JAN 1940.
Subsequently her first UK PP was 01 JAN 1945.
Then, during a renewal of her first UK digital PP the new document was issued with DOB 14 JAN 1945 apparently an administration error. Now, of couse, it was all on a database and network!
So, I chose to ignore it since it did not affect us at all except that various everyday transaction such as Utility Bills and Electoral Roll still showed 01 JAN 1945. Easily fixed since the Primary Source document was the UK PP.
Just once, about 5 years ago, we passed Immigration at Manchester Airport on return from Europe and a young officer challenged her DOB saying it was different to his database record (Huh?). I was able to show him her previous UK PP (expired) and that convinced him. He told me they were seeing increasing numbers of forged UK PPs.