Why are there no options to accept or decline via iOS to invites sent from a Google calendar?

To accept a calendar invite sent from a Google calendar user and have it appear as such in my Apple Calendar, I always need to accept on one of my Macs. My iPhone 16 Pro Max running iOS 18.5, doesn't show the "Accept" or "Decline" options that I see on my Macs. I can choose the "yes" in the Google invite but this only allows me to ensure that the Google sender of the invite gets the accepted status. It will continue to show in my Apple Calendar as tentative. Is this a problem on Google's or Apple's side?