Wandering trader llamas don’t despawn, this causes them to slowly build up in your world which creates lag, and clutters up areas. Especially when you don’t know where they are. further testing will be implemented when I update to the 1.16.210 update.
Related issues
Comments

Thank you for your report!
We're tracking this issue in MCPE-44312, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki