I use PHPTools with remote development (ms-vscode-remote.vscode-remote-extensionpack) and find that XDebug is basically useless. I have to disable it and use PHP Debug (felixfbecker.php-debug) to use debugging.
What happens while using PHPTools is it stops at a breakpoint, then I can step through code for a very random amount of time, could be 3 seconds, could be a minute, then it appears to loose connection and I get a message about no such breakpoint and the page hangs indefinitely.
I don't recall if PHPTools supports XDebug with remote development?