@Tadas247
Please tell me/us, do you using all the features by FortiClient or something like Web-Protection only?
Immunet is your 2nd AV running as "companion" even in real-time with full features enabled?
You may like trying this tool below, it's even useful to check for broken leftover as autoruns or drivers of software already uninstalled from your system.
Another highly recommended feature for security purpose, automatically scanning all files for (possible) detection on VirusTotal.
See what programs are configured to startup automatically when your system boots and you login.
docs.microsoft.com