Canada is operating legacy Hornets (CF-188 model, which is basically an F/A-18A/B). Those planes are old – they were built in the 80s. Their airframes are nearing their end of life, if they have not reached it already- which in a lot of cases they have.

One way to tell them apart from other legacy Hornets is the false canopy painted on the bottom

It’s generally not a good thing when the majority of the pilots flying your fighters are a lot younger than the planes. Yes, in some cases it’s fine (e.g. with the B-52 or transport planes, which are subsonic and do not pull high-G maneuvers) but not for fighter jets that are still supposedly in front-line use.

Australia sold (for a veritable pittance) a bunch of their old Hornets to Canada for use as spares to try to keep them going until replacements come into service.

The USAF never operated Hornet; it was the USN and USMC that did. Both have long since retired the legacy models, and their last legacy Hornet models were newer than Canada’s! The USN is the only remaining US Hornet operator, but they use Super Hornet which (in spite of the name and designation) actually isn’t the same plane. Even the Blue Angels fly Super Hornet now.

I’m fairly certain the USAF wouldn’t take Canada’s Hornets even if they were offered for free.