Welcome @mostaffa !
The ability to not provide the max_length parameter for SQLite is a change in Django 5.2.
In the Models portion of the Minor features section at: Django 5.2 release notes | Django documentation | Django :
CharField.max_lengthis no longer required to be set on SQLite, which supports unlimitedVARCHARcolumns.
It’s also highlighted in the current version of the docs for CharField
This change was introduced for PostgreSQL in Django 4.2. (Django 4.2 release notes | Django documentation | Django)