The only consideration that need be accounted for is the lack of higher level spells or abilities. So, while they are 4th level PCs, nobody will be slinging a Fireball, and if you've designed an encounter that required Fireball or some equivalent to bypass or survive, you're going to get a TPK. Or at the very least, you'll have unhappy players.
This isn't something new- I had a DM in a high-level 1Ed campaign who had an encounter that just stymied the party. When we retreated and stopped gaming for the evening, he asked us why we didn't cast "X" spell.
Which is when we pointed out "X" was a 9th level spell, and the party had no arcane spellcasters with access to higher than 8th.
This isn't something new- I had a DM in a high-level 1Ed campaign who had an encounter that just stymied the party. When we retreated and stopped gaming for the evening, he asked us why we didn't cast "X" spell.
Which is when we pointed out "X" was a 9th level spell, and the party had no arcane spellcasters with access to higher than 8th.