I hear pops or loud clicks from the speakers when switching inputs or powering on/off. Is that damaging?

The soft click inside the receiver is a relay doing its job and you can ignore it. Small pops through the speakers at normal volume are common and harmless. Loud cracks on every switch are the one version worth acting on.

Separate the two first, because people lump them together. The mechanical click at power on, power off or an input change is the output relay connecting or disconnecting the speaker terminals; that is protection working, not protection failing. If it were silent I would be more curious.

Pops through the speakers are electrical: a small DC step or a burst of noise reaching the amplifier stage during a transition. At normal listening levels the energy is tiny and a tweeter shrugs it off. The problem case is a loud, sharp crack, and especially one that appears at every switch regardless of source and volume, or one that is getting worse over months. Repeated high-energy transients are unkind to tweeters, whose voice coils are small and not built for surprises.

Hygiene that removes most of it: lower the volume before you change sources or formats; keep the AVR firmware current; and find out whether one particular device is the trigger. A source that flips abruptly between PCM and bitstream (some TV apps and streaming boxes do this at every menu) is the usual origin. Fix that device's audio output to one format and the pops usually stop. The AVR is not the culprit here, it is the messenger, and it has been shouting the message through your speakers.

Also keep the old rule: AVR on before the sources, and off after them. That way the sources start and stop into an amplifier that is either muted or already handling it.

Loud pops on every switch, source-independent, or clearly worsening? Authorised service, and stop pushing the volume until it is looked at. Occasional small tick at sane volumes? Nothing to buy and nothing to fix. If you are unsure which category you are in, describe the pattern to us on WhatsApp (when it happens, how loud, which source) and I will tell you which one it is.