Thanks for the reply.
I previously tried disabling Bloom while playing on my world, but it didn't help. Today, after launching the game, I disabled this option in the main menu settings and entered the world, and everything was fine. Just to make sure, I turned bloom back on and off but the effect on light sources was still visible even though bloom was disabled in the settings.
I think it's a bug, because after exiting the world and re-entering, once again everything was fine.