Windows malware on Macbook Pro?

A couple of years ago I used an asus laptop, it got infected with rootkits and i think my mac got infected afterwards by an external hard drive that i also used on the asus. as I said, Access rights / user rights are modified so I cannot make changes to certain files and programs myself. When I do a clean install I see a lot of error messages in the log files and the button with "send to apple" does not work. When my macbook goes to sleep and then activates the mac, I first see a login screen with a loading bar, as if something is being installed, this screen then disappears after which I enter my password. sometimes the login screen returns a second time (asks for password again). No I’m not paranoia / scared.

These are just examples, I'll spare you the whole list of bugs. But I do find it annoying that these things are never taken seriously by apple. I paid a 250 euro guarantee on top of the purchase price, with the promise to be insured for everything. When I first went to the apple store with this I was looked at as if I am crazy. I recently decided to try again this way, but in my opinion I am again not taken seriously....

Hello Barney, thanks for the reply. I have one question left. When I use diskutil -list in terminal, I see that the efi partition is in MSDOS format. Is this normal?