microsoft mail sends weird icon to dock

If you are referring to that extra little icon, it's an indication that the "handoff" feature is being used.

Pick up where you left off with Handoff on Mac - Apple Support

Handoff allows you to continue with the same work flow as you move from using one Apple device to another, from the iPad to the Mac for example. The feature can be turned on and off. Pease see the link above.

That icon is the Chrome Bowser, not sure but perhapssomone is viewing yur screen...

Safe Boot, (holding Shift key down at startup), does the problem occur in Safe Mode? Could take 10 minutes.

Safe mode attempts to repair Disks & clears lots of caches & loads safe Drivers, & prevents loading of 3rd party extensions, so if Safe Mode works try again in regular boot.

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Pastebin is a good place to paste the whole report if you capture the URL while there…

https://pastebin.com/

Whew, they've changed pastebin & made it harder, but after pasting in, click Create new paste button, then Embed button, then copy the URL...

<script src="https://pastebin.com/embed_js/KuvnghqA"></script>

The important part of the above is between the quote marks...

https://pastebin.com/embed_js/KuvnghqA

If pastebin is a problem for you then workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...