My basic tip when it comes to browsers is:
For you who use Microsoft 365 - use Microsoft Edge
Are you a Google fan - use Google Chrome
Use multiple browsers to protect your privacy:
Edge for all Microsoft sign-in
Chrome for all Google sign-in
Make sure to always:
Keep the browsers you use up to date
Have your device, Windows, Mac, mobile phone, tablet up to date
Using the latest version of Windows, MacOS, Andriod and iOS
Since there is a risk of information leakage as Google has the principle that they own all your data, it could be that your Microsoft data and login credentials become available to Google. That's why I like to use different browsers for different purposes. If you are a Microsoft 365 business customer, the principle applies that all data is yours - Microsoft neither can nor uses your data - it is only yours and you decide over it.
Edge Advantage
A big advantage of Microsoft Edge when you use it on Windows is that it inherits your logging in to Windows. That means fewer logins in the browser, because Edge already knows who you are and uses your Windows login credentials.
Another benefit of Edge, for those of you who use Microsoft 365 for Business with the Azure AD Premium license, is that all settings follow you, and that those settings are stored in Microsoft 365 with the same privacy and security protections as everything else you have in there. Getting their settings like favorites, collections and is convenient, and these follow you across all your devices - provided you're signed into Edge on them. Similar functionality is also available in Firefox and Edge, but the settings are saved at Mozilla and Google datacenters instead - thus a lower level of security applies compared to Microsoft 365 for Business. For those who use a Microsoft account to sign in to Edge, then the settings are saved at Microsoft's datacenter, but not with the same high level of privacy and security compared to the M365 business versions for company, school and organization.
Edge is available for Windows, MacOS, iPhone/iPad and Android
New version of Outlook
Soon there will be new versions of Outlook. If you're using Outlook in your browser, make sure you have a supported browser:
Windows 11: Microsoft Edge, Mozilla Firefox, or Google Chrome
Windows 10: Microsoft Edge, Mozilla Firefox or Google Chrome
MacOS: Microsoft Edge, Apple Safari, Mozilla Firefox, or Google Chrome
Linux: Outlook.com and Outlook on the web work in either Firefox or Chrome on Linux, but some features may not be available.
If you are using an old browser (Internet Explorer, Microsoft Edge (older version), New Microsoft Edge<=65, Safari <=11, Mozilla Firefox< =63, Opera <=53), you will see the light version of Outlook - a variant with poorer functionality. Keep in mind that Internet Explorer is no longer supported and no longer receives any security updates - that product died years ago = don't use it.
Your phone/tablet should have at least these versions:
A phone or tablet running Android 5.0 and up.
An iPhone, iPad, or iPod touch with iOS 10.0 or later.
A phone running Windows Phone 7.5 or later.
There are two familiar ad blockers/pop-up blockers that make Outlook on the web unsupported, so these you should not use:
AdBlock
Ublock
The new Outlook for Windows
When Microsoft will release the new Outlook for Windows is yet unknown. The product is available for testing, and it is based on the Outlook on the web version. My guess is that the same browser requirements apply when using the NEW Outlook for Windows as for Outlook on the web.