SUMMARY

Screen does not lock automatically when certain chrome/chromium tabs are open (e.g. when playing media). This may represent a security issue.

For some this may be a feature (e.g. if you are playing a video, you may not want your machine to lock).  However, in many cases it is a serious security issue. For example: you are listening to music, you must leave the machine for a moment, something ends up preventing you from going back to the machine for a longer time than expected, you feel safe supposing that your machine will anyway be autolocked and the machine may remain with your session open and usable by anyone (to read your data including sensitive info or to do something malicious) forever.

This is something that should most definitely made at least configurable.

Furthermore, there is really no reason why merely listening to audio should prevent the machine from autolocking, since screen locking does not prevent audio from being heard.

STEPS TO REPRODUCE
1. Open your email client, start reading email
2. Open chromium
3. Go to spotify and start playing a song
4. Leave the machine alone for 2 hours

OBSERVED RESULT

After two hours anyone passing by will be able to read your email or to send email under your name.

EXPECTED RESULT

The machine should autolock, you are merely playing audio. If there are technical difficulties in distinguishing whether the machine that is playing media is playing just audio or also video, it should be possible to configure it so that media playing cannot inhibit screen auto lock. 

SOFTWARE/OS VERSIONS

Operating System: Manjaro Linux
KDE Plasma Version: 5.26.4
KDE Frameworks Version: 5.101.0
Qt Version: 5.15.7
Kernel Version: 6.1.1-arch1-1.2 (64-bit)
Graphics Platform: X11