Logic Pro X scans plugins every time I open it
The problem randomly started to occur without even installing new plugins.
iMac Line (2012 and Later)
Please provide more details and clarity in your question.
Which version of Logic are you running?
Does it happen "every time", as it says in the subject, or does it happens "randomly", as it says in the body?
Which plugins does it scan? All of them? Certain 3rd party plugins?
Is there an error message? After scanning, do all the plugins validate successfully? If not, which one(s) fail?
FYI, Logic (or any DAW) will rescan anytime you update a plugin, not just installing new ones.
What happens if you open Logic Pro X -> Preferences -> Plug-in Manager..., select all plugins, and then Reset & Rescan Selection?
Also, look in your plugins list (Logic Pro X -> Preferences -> Plug-in Manager...) for any unchecked or unvalidated plugins, any errors or warnings.