I have noticed whenever I use the markup_escape() function to format the metadata output from playerctl, I no longer receive notifications for when media is paused and unpaused with Youtube Music Desktop. This problem immediately alleviates itself whenever I remove any invocation of the function from my command input.

Sample command:
playerctl metadata --format '{\"text\": \"\", \"tooltip\": \"{{markup_escape(playerName)}} {{markup_escape(title)}} - {{markup_escape(artist)}}\\n{{markup_escape(album)}}\", \"alt\": \"{{status}}\", \"class\": \"{{status}}\"}' -F

Working command:
playerctl metadata --format '{\"text\": \"{{title}} - {{artist}}\", \"tooltip\": \"{{playerName}}\\n{{title}} - {{artist}}\\n{{album}}\", \"alt\": \"{{status}}\", \"class\": \"{{status}}\"}' -F 2>/dev/null | sed -u 's/&/&/g'