So far I've only taken one bus but I didn't see any fareboxes or places to tap the Tap card. I asked the driver if I need to tap the card but I only got the hand gesture which I interpreted as "move to the back of the bus". People are just boarding the bus through rear doors and taking seats. But I didn't find anything about fare free rides on the metro website. So are the rides actually free?
LA Metro has not technically waived fares; officially, the policy is
While you are not expected to use the fare box or TAP validator at the front of the bus, please be in possession of fare during travel.
Fare enforcement is suspended, however, so for all practical purposes, bus rides are currently free.
As with a number of other U.S. public transit agencies, fare-free rides may be permanently instituted for low-income riders after the pandemic; a pilot program is underway in Los Angeles County.
As Doc notes in a comment, this answer applies only to buses operated by the MTA. Other agencies like BCT, Big Blue Bus, Foothill Transit, or OCTA will have their own policies.