Some files have not passed the integrity check. Upgrade to 28.0.4 mail app

Just did the upgrade to 28.0.4 and now this appears in the Security & setup warnings: Some files have not passed the integrity check.

EXTRA_FILE. Is the signature.json not up to date, or are there obsolete files?

Any help is much appreciated!

Technical information
The following list covers which files have failed the integrity check. Please read
the previous linked documentation to learn more about the errors and how to fix

- mail
		- vendor/ezyang/htmlpurifier/library/HTMLPurifier/DefinitionCache/Serializer/URI/4.15.0,3478238e680361cd87bf880f5b3cc50a1e7abc6c,1.ser
		- vendor/ezyang/htmlpurifier/library/HTMLPurifier/DefinitionCache/Serializer/HTML/4.15.0,100a0d442686872045400b774dcb082c945a1908,2019080701.ser

Raw output
    [mail] => Array
            [EXTRA_FILE] => Array
                    [vendor/ezyang/htmlpurifier/library/HTMLPurifier/DefinitionCache/Serializer/URI/4.15.0,3478238e680361cd87bf880f5b3cc50a1e7abc6c,1.ser] => Array
                            [expected] => 
                            [current] => 403272903ab6fd6acf8073eff7d4449d1d3c14a96ea299c257a66b334e44b09b0554c4f3be88a269f233dc1ec7e077e739d7a6d2c744dc9e1dadd7757ed1ca09

                    [vendor/ezyang/htmlpurifier/library/HTMLPurifier/DefinitionCache/Serializer/HTML/4.15.0,100a0d442686872045400b774dcb082c945a1908,2019080701.ser] => Array
                            [expected] => 
                            [current] => c68d95b7adc0174b7dcdc500b4480d4e29378ecda31c124be014323035795d47678e4d77629e7cfc8a667f6ec49863274ee48654b0a93d18e3a20c9f0febcdbf




linux 6.1.0-18-amd64 on debian 12.5

According to the documentation, both “EXTRA_FILE” can be removed. After doing so and executing a rescan, the files re-appear and the error message in the administration settings remains.

The mail app was updated today to version 3.5.8 but this didn’t solve this error.

What else can be done?