Fianchetto trade pattern

Hello,
About this pattern -
https://lichess.org/analysis/5rk1/5pbp/6p1/8/8/4B3/3Q4/7K_w_-_-_0_1

When I'm black I always take action after the queen align this way with the bishop & move the rook to prevent the trade of bishops

When I'm white when I get the chance I'm always trying to get that trade done! so if the rook isn't moving I immediately Bh6 and force the trade

I thought it's a universal truth until I've seen a game between two GMs that didn't care for that trade, and I started questioning myself... I thought it's a no-brainer move to trade this bishop who's guarding the king position...

Do you have any thoughts on that kind of pattern?

Can you give a reason when it's good or not trade this fianchetto bishop?

The game I've seen is this one -
https://youtu.be/B2uVvaupBDE?t=78
(The timestamp is when the queen goes to a battery with the bishop. and to my dismay black didn't concern from that... for a lot of moves. what have I missed?)

Thanks :)

Sometimes it's useful, sometimes not. :)

@MrPushwood said in #2:

Sometimes it's useful, sometimes not. :)

Yea thanks :)
Do have an idea in the attached video why black does not need to guard its fianchetto bishop with its life?

You need the bishop if the opposing player has the bishop because you will have darksquare weaknesses if you dont have it and he does.

But i suppose it depends on the center. If the center is totally close, you trade it and maneuver your queen to those dark squares if you have the time. If you dont have the time, probably dont trade it, as you wont have reinforcements since there is little space to bring some.

If the center is wide open, Keep it. The bishop can land on the center of the board, attack both king and queen sides and still cover the key darksquares to keep you safe. and in some variations, for instance the Benko where white traded his bishop for a knight, the bishop becomes such a monster that even trading it for a rook is a bad trade for you.