YouTube and Twitter won't remember display mode settings.

Hello. I'm currently using a 2020 13'' MacBook Pro running Catalina 10.15.5 and Safari 13.1.1.

I do not have dark mode enabled system wide but I do turn it on with certain websites, such as YouTube and Twitter. These sites have individual settings that enable dark mode within that website. I turn on Dark Mode through my YouTube account settings, and I set Twitter to the "dim" display mode.

The problem I am encountering with these websites under Safari is that after about a week or so, these two websites' display modes keep getting reset back to the normal light modes, but I still retain my other website settings and am still logged in. I have to go back into each sites display options to turn the dark mode back on. This works for about another week or so when these settings get reset again.

I do not encounter these issues using Facebook. I turned on dark mode there and so far this setting hasn't reset to light mode.

Would this be a problem with the websites themselves or is this a bug with Safari? Has anyone else encountered this issue with Catalina and Safari?