Here is a lengty-er reply.
https://support.google.com/chromecast/answer/3265953?hl=en
This is for the missing button, it should be there, but for some reason it is not, as you guys have confirmed, the site is cast supported.
AS for this, google has updated the support site, since i have googled chrome cast and got this.
https://support.google.com/chromecast/answer/2998456?co=GENIE.Platform%3DAndroid&hl=en
And they now want you to setup Google HOME.
So i assume Google HOME is reqired on Android 10 to properly enable cast buttons, just so the compatition has issues with it.
On Android 9 this was not reqired.
Like the guy with the amazon firestick and my with my 2019 LG-oledtv that is not listed to have built in chromecast, just google assistant, even though the whole thing is just WIFI DIRECT/miracast combination , that the tv supports.
This are kinda related.
I currently do not own a Chromecast device, and i do not plan on buying it either. So cannot test this theory.
I did pay for a SMART TV and a SMART phone. Why would i need to buy a SMART device to make them pre android 10 SMART?
They do work on my older phones, just like for you guys, just not on the ones with android 10 later than february security updates.
Google has silently made the "screen share" button Chromecast only.
LG help site:
https://www.lg.com/us/support/help-library/screen-share-screen-mirroring-device-to-tv-CT10000018-20150637965681
Optipon 4 works like a charm on ASUS LG AND SAMSUNG devices.
Similar to that amazon stick thread, where we now only can cast apps only.
https://support.google.com/pixelphone/thread/6805429?hl=en
Not a very nice move from google.
This states that even pixel phones cannot "SCREEN SHARE".
And motorola is closeset to stock android 10 rom as it gets.
Nothing i could find exept from forums from other phone manufacturers, that "screen share" is no longer "supported" *i kinda meant sarcasticcaly this:works*
Sideshare:
https://www.cnet.com/how-to/cast-and-mirror-an-android-screen-to-your-tv-in-three-easy-steps/
Here is a guide from CNET to chromecast.
I think in thory if you do this, you should get that button back on site.
As for me, and the firestick user, i think motorola needs to do something with android to make it work.
Sadly. Though it is currently just a theory.