Zardnaar
Legend
Well then, you'll have to ask for errata to the 2024 PHB, p. 363:
Challenge Rating
Challenge Rating (CR) summarizes the threat a monster poses to a group of four player characters. Compare a monster's CR to the characters' level. If the CR is higher, the monster is likely a danger. If the CR is lower, the monster likely poses little threat. But circumstances and the number of player characters can significantly alter how threatening a monster is in actual play. The Dungeon Master's Guide provides guidance to the DM on using CR while planning potential combat encounters.
They'll also have to errata the Basic Rules, as this text is also printed there. Oh! And the Rules Glossary, and the SRD 5.2.1!
So. You were saying.
Its not saying anything about 4 levels though that you claimed.
Its merely pointing out higher CR critters are more dangerous.
You're also cherry picking. There's a table laying out what you can do. Higher CR critters are more dangerous, be careful if PCs outnumbered 2-1 or more.
That's also the PHB, not the DMG where the actual rules are.
Since you've never run 5.5.......
The actual rules very similar to 4E.