I live outside the U.S. and my package has been stuck in customs for a long time.
International shipments can take a very long time to reach their destinations. Getting held up in customs is extremely common, especially given outside circumstances such as COVID-19 and Brexit. Packages taking up to 3 months to get delivered is very normal right now. So try not to rush to assumptions about it being lost in the mail. Chances are, it's just stuck in a giant customs queue.