aptitude says I'm running outdated binaries

Question

whenever I run

sudo apt install package-name

I get the following message at the end of the output:

User sessions running outdated binaries: user @ session #2: plasmashell[1666]

this stays after rebooting

I'm running plasmashell 5.20.5 on debian 11 (as dual boot with windows 10).

How do I fix this?

thank you.