When doing an sfdx force:mdapi:deploy of a Process Builder flow I get the error Property 'flowTransactionModel' not valid in version 50.0 However the flow deploys using Change sets. Anyone else see this type of error? 

Hello,
In a Spring '20 sandbox I created a custom object and a custom Lightning Record page that contains a Lightning Web Component.  When I look at the mobile app on my phone it shows up great in the custom apps but if I look at the object via the 'Mobile Only' app the default record page shows up. 
In the Lightning App Builder activation dialog there is no place to assign the page to the Mobile only app. I went thru the trailhead and documetation about customizing the Mobile Only app, but I could find no documetation on displaying Lightning Record pages in Mobile Only.
Any insight anyone has would be appreciated.

When doing an sfdx force:mdapi:deploy of a Process Builder flow I get the error Property 'flowTransactionModel' not valid in version 50.0 However the flow deploys using Change sets. Anyone else see this type of error? 

When doing an sfdx force:mdapi:deploy of a Process Builder flow I get the error Property 'flowTransactionModel' not valid in version 50.0 However the flow deploys using Change sets. Anyone else see this type of error? 

Since a week or so I suddenly get `INVALID_SESSION_ID: Session expired or invalid` errors when trying to deploy to a sandbox. Around the same time, I suddenly started seeing the line `*** Deploying with REST ***` when running an `sfdx force:source:deploy`.

I never used to see my token expire before. Now I have to daily go and re-auth my org connection.

This seems like a regression. What's going on?