I cannot log in, I can change password, that lets me in briefly, for instance to read/answer messages but as soon as I try to open a community I'm logged out again. Someone asked me to help them moderate a community but I can't be of any help now.
How are you accessing lemmy.world? Via desktop browser? Try clearing your cache. Via mobile on Android, clear android's app data for your app. Also try an explicit logout to ensure your session is cleanly torn down on both sides.
I'm in using microsoft Edge, probably the only browser I was sure had never seen you site and I am in. But that's a lot of browser to clear..
I am using firefox, chrome, opera, vivaldi, connect on android.
I can now log in using android again. Let's try firefox