My desktop browser (Firefox and Chrome) on Linux just shows me a perpetual spinner icon when I click login. I had the same problem when I tried to sign up. My current work around is to access Lemmy on mobile only.
I’m not a fan of infinite spinners. ♾️
Infinite spinner is most likely caused by an incorrect password.
I checked my password on mobile and found that I have been trying to login on Desktop with a password that is “off-by-one” char. lol 🤦