It was the same at the beginning of last generation. They tried to use the new launch as an excuse to raise prices. Though things returned to normal fairly quickly.
Just look at the price of PS4 launch games in UK:
Assassin's Creed 4 - £54.99
Its a weird situation in the UK. I think its more down to the retailer to price and margins as well as publishers rrp.
At launch, it was £55 per game.with a few months dropped down to £45-48. But over the years its gradually gone up as consumers are used to spending more on bigger releases. Games are averaging at £50, now. I'm assuming this will follow the same trend - £55 for launch PS5/Xbox Series X games.
I'm doubt it will go any higher than it is now though, for us anyway.