Filter of plugin Fields - Editor not applied anymore after change to Safe HTML and back to Text

Steps to reproduce the issue

create a custom field of type Editor (editor)
enter some HTML code into this field for an article, e.g. Hello World! (it doesn’t matter whether you use TinyMCE or CodeMirror)
the HTML gets filtered
now edit the plugin Fields - Editor and change Filter to Safe HTML
again, enter some HTML code into the editor field (see example above)
the HTML does not get filtered
edit the plugin Fields - Editor again and change Filter to Text
the HTML does not get filtered anymore, not even after saving the article nor after changing the custom field content nor for new custom fields of the type Editor (editor)

Expected result

The HTML content of all editor fields should get filtered after resetting the filte to Text. I.e. the content of existing fields should not be changed immediately after changing the filter, but on the next save of the article. The content of all new editor fields should get filtered immediately when first saving content in this new field.

Actual result

HTML content for fields of the type Editor (editor) does not get filtered anymore, neither for existing nor for new fields.

System information (as much as possible)

PHP Built On | Linux dd45920 4.15.0-128-generic #131~16.04.1-Ubuntu SMP Wed Dec 9 17:33:47 UTC 2020 x86_64 Database Type | mysql Database Version | 5.7.28-nmm1-log Database Collation | utf8_general_ci Database Connection Collation | utf8mb4_general_ci PHP Version | 7.3.22-nmm1 Web Server | Apache WebServer to PHP Interface | fpm-fcgi Joomla! Version | Joomla! 3.9.23 Stable [ Amani ] 24-November-2020 15:00 GMT Joomla! Platform Version | Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT User Agent | Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36

Additional comments

Tested with German Joomla! installation package and Blog demo data.

joomla / joomla-cms