iPhone freezes with one specific Messages thread

Whenever I open one persons texts my phone freezes and it won’t let me text them, however other messages work with other people. They sent a video and a voice memo last and I thought that might be the reason but other apps are working playing the same video. I’ve gone through and deleted large files and other things but I can’t fix it, I’ve restarted 3 times and nothing works

[Re-Titled by Moderator]