1) The battery may need to be replaced.
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2) Sequoia 15.6 is the most current macOS.
What's new in the updates for macOS Sequoia - Apple Support
3) The Storage Drive is nearing a point where it is becoming to full to preform at full speed.
Moving documents to external hard disk or… - Apple Community
4) The Mac has not been restarted for 21 days.
Generally this is not a problem, but it will likely preform better if it is restarted weekly.
5) macOS has all of the necessary Security to keep your Mac Safe.
Third-party junk-ware like Intego, do nothing but slow down your Mac cause all sorts of problems.
My advise at this time.
Have the battery check and/or replaced.
Update to the latest Sequoia macOS 15.6 version.
Completely uninstall Intego as per the developers directions.
Restart in Safe Mode followed by a normal restart and test for a few days.
Start up your Mac in safe mode - Apple Support