I agree that the gang of 8 stuff was atrocious.
But also remember that it never went anywhere.
Rubio in this administration has been pretty hardline against immigration and as SOS he actually does stuff about it.
it was even longer ago than that, 2013 that he did the immigration stuff. (which again, never went anywhere).
He had already moved away from it by 2016.
Lately Rubio has been revoking visa statuses and deporting people to third party countries.
Which is like the complete other end of the spectrum.
Now who knows what could happen. Would do a total 180 again if he became president?
It's possible, but seems unlikely.
If you want to be an effective GOP politician now, you HAVE to be anti immigration.
It's consistently listed as one of the biggest issues with voters (economy is almost always first but immigration is right up there).
And Rubio is an effective politician, if nothing else, so he knows that.
edit: i still think Rubios negatives are just that he's short/small and kind of has a weird lisp
it's really petty but i think that stuff matters with voters.
desantis also has this too in being short and talking like a nerd.
vance is probably the most charismatic but for him its the other end where it almost comes off as too polished.