Waited over THREE HOURS and am still barely feeling any affects. Are my tabs fucked?

Took 2 tabs which amount to a total of 500ug (but are probably less since tabs are typically underdosed) 3 hours ago and while I’m feeling some light effects genuinely nothing else is happening to me. Last time I did these tabs they worked very well but didn’t take this longer to kick in. Are my tabs potency lost or something?