Opening web page from Thunderbird opens new Firefox window
I run Thunderbird on an email-only system which I can access from LAN or remotely.. I "ssh -X" to that system and run Thunderbird, which displays on my workstation. Until an update a few days ago, when I clicked on an http/https link in Thunderbird, if there was an instance of Firefox running on my workstation, the link would open in a new tab on the most recently accessed Firefox window. If there was no instance of Firefox running on the workstation, then Firefox would be started on the email-only system, which would display on my workstation. After the recent update, the behavior has changed: clicking on a link always opens Firefox on the email-only system, not a new tab on the workstation.
Running Thunderbird 78.14.0 on Centos 7.9 email system, Firefox 94.0 on Fedora 33 workstation.
Any suggestions on how to have the previous behavior?