I compared Microsoft 365 with Google Workspace, so Google suspended my account

From reviewing your site it appears to be an official Microsoft website as you are using their trademarked logos as your favicon, the Microsoft design style and all around the site without properly notifying visitors up front that you are not officially affiliated with Microsoft. If you are, then you should have this listed on the site and link to your partner status validation with Microsoft.

This is why it has been marked as a phishing site due to not properly identifying your affiliation. There is no footer with the details of the business behind the site and the about us page does not properly identify your company or business information which is very common on phishing websites.

Best practice is to come up with a unique web design that is not easily comparable to the products main vendor that you are creating a service for. Once you have properly identified the site and changed the design you might be able to get unsuspended, but for now the site looks and feels like a phishing website.

At first glance, it may be because you use the Office and Microsoft logos, in addition to mimicking Microsoft design, including the SegoeUI font? Your About Us section also features the Microsoft logo, so some people could get confused that you aren't affiliated with Microsoft.

Tbh, had you not posted here and I'd come across your site, I'd think something is off because of how close the imitation is. So maybe the solution is to more clearly state that you are not affiliated with Microsoft and maybe change the design a bit to not mimic Microsoft so much.

Going to Microsoft with a site like this might result in a cease and desist instead of them helping your cause.

Seems reasonable: website looks shady, doesn't make it clear it's not Microsoft, doesn't have any contact or company/owner information. If I stumbled upon it I'd just assume it's purely a scam

Record everything and get a lawyer, you might be able to sue them and earn a large sum. Let Microsoft know maybe they could support you legally.

Not an expert in any of this...but...

It mentions phishing. Could mentioning Google in an add trigger something like this?

Hanlon's Razor also applies to automatic processes.

Your website looks way too much like an actual Microsoft website. If you showed this to me without telling the URL, it would take me a minute to realize it's not a real Microsoft site.

I think an actual human reviewer would have come to the same decision in this case.