I also had the exact same bug on my realm on bedrock edition fpr ps5. So I tried to download the world via Minecraft Windows Edition and my attempt was eventually successful. I still can't download it on my ps5 but in case something goes wrong or the world data gets damaged, I have a backup on my laptop.
Maybe this can help you to save your world data just in case something goes wrong.
Vladislav Wilhelm
I also had the exact same bug on my realm on bedrock edition fpr ps5. So I tried to download the world via Minecraft Windows Edition and my attempt was eventually successful. I still can't download it on my ps5 but in case something goes wrong or the world data gets damaged, I have a backup on my laptop.
Maybe this can help you to save your world data just in case something goes wrong.