Although some arguments can be made that the native Indians were mistreated by some priests in the mission system, the people who caused the vandalism should know that Father Serra was not one of those priests. he was, by all accounts, a great and humble man who devoted his life to bringing Christianity and civilization to that part of California.
But to many of the Far Left, it doesn’t matter. He gets lumped in with everyone and everything involving the mission system.
And, therein lies the problem. It is not just the founding and very existence of the United States that these idiots want to erase; Christianity must go as well. They are Socialist/Communist true believers and they now have a lot of "useful idiots" to help them to their goal. We are under attack from within, all paid for by George Soros' money.