luceos I did more test but still can not figure out the reason. just excluded the possbilities of if there will be any conflict between extensions. In my case, it did seem related to Flarum 1.3.0
You may would like to test it by your own, here is the link of my test forum: www.gingastation.cn
you can login with user username:test password:test1234
and username:test2 password:test1234
and have a try
and this is the flarum info of the site:
Flarum core 1.3.0
PHP version: 8.0.16
MySQL version: 8.0.24
Loaded extensions: Core, date, libxml, openssl, pcre, sqlite3, zlib, bcmath, ctype, curl, dom, filter, ftp, gd, gettext, hash, iconv, intl, json, mbstring, SPL, session, pcntl, standard, PDO, mysqlnd, pdo_sqlite, Phar, posix, Reflection, pdo_mysql, shmop, SimpleXML, soap, sockets, sodium, mysqli, sysvsem, tokenizer, xml, xmlreader, xmlwriter, zip, fileinfo, exif, gmp, Zend OPcache
+-------------------------------------+---------+--------+
| Flarum Extensions | | |
+-------------------------------------+---------+--------+
| ID | Version | Commit |
+-------------------------------------+---------+--------+
| sycho-advanced-extension-categories | v0.1.3 | |
| flarum-tags | v1.3.0 | |
| flarum-subscriptions | v1.3.0 | |
| flarum-nicknames | v1.3.1 | |
| flarum-mentions | v1.3.0 | |
| flarum-lang-english | v1.3.0 | |
+-------------------------------------+---------+--------+
Base URL: https://www.gingastation.cn
Installation path: /www/wwwroot/gingastation.cn
Queue driver: sync
Mail driver: smtp
Debug mode: off