SQL: Regex for replace query - sql

Question

I have SQL table as UserInfo with columns [id, username, details]. I need to update a part of a string from the column details.
For example. details column will look like,
{"username":"user.sample#nomail.org","rollno":45,"gender":"male"}
P.S: In actual DB this column is really long with more details, for example, I quoted above few details.
Condition is that the username value in the details column should be the same as the value in the username column.
I have n number of records mismatching in the DB, meaning username column value is different from username information in the details column.
Ex
id - username - details
23 - new-user#nomail.org - {"username":"user.sample#nomail.org","rollno":45,"gender":"male"}
Hence I am trying to replace the "username": "value" in details column with the username column value
EX - Expected should be like,
id - username - details
23 - new-user#nomail.org - {"username":"new-user#nomail.org","rollno":45,"gender":"male"}
For updating UserInfo, I am trying like
update UserInfo
set details = replace(details, \Regex\ ,"username:"+ username)
where id not in (select id from UserInfo where details like '%'+userid+'%' )
I need to regex pattern matching, ["username":"mail-id"], so that I can able to replace that particular string in that details column.
Any idea/suggestion for the regex pattern would be helpful