14.0 breaks --allow-remote when another instance of firefox is in use

Before upgrading to 14.0 I was able to start TB with the --allow-remote option to open urls from the command line in TB, while also using another instance of firefox (128.3.1-esr on debian linux) for other tasks. TB and my standard "system" firefox worked independently: I was able to start each one, and to open urls from the command line in either of them.

After upgrading TB to 14.0:

• TB --allow-remote still works as expected, provided the system firefox instance is not in use
• If system firefox is already in use, and I start TB with --allow-remote, I get a new tab on the system firefox. Expected result: TB should start instead.
• If TB --allow-remote is already in use, and I start the system firefox, i get a new tab on TB. Expected result: the system firefox should start instead.
• TB without --allow-remote works as expected: I can start either browser independently

The only partial workaround I found so far: first start TB with --allow-remote, then start the system firefox with the --new-instance option; this at least allows starting both browsers and opening urls from the command line in TB (though I am no longer able to open urls from the command line on the system firefox, the url gets opened in TB instead, it looks like with TB 14.0 there can only be one firefox instance accepting remote urls)