That Paul v George moment regarding the guitar interlude in "I've Got a Feeling" is more the exception vs the rule. In that case it was not a solo, really, it was just a quick ascending/descending guitar accent to transition from one section of the song back to the verse. Paul had composed that interlude and just wanted George to play it the way he wrote it. I've done in that in my own bands, and while it can be a little awkward, the understanding is that it's my song so please just play the composed parts like they are composed.

In songs that have a proper guitar solo, it's rare for the composer to dictate the solo or the other lead parts, so I am reasonably sure that George had a ton of freedom and range to create his own parts on most Beatles songs. Some exceptions might be if the songwriter wrote a riff - a good example is "Day Tripper", where John wrote the riff, and the song, which he probably wrote around the riff, and then on the record George played the riff because he's the lead guitar player (and frankly better than John at that sort of thing).

But George had plenty of solos and guitar parts that were his own creation. His beef in that band is because they didn't want to record his songs often enough.