There's old school spirit in this here 5E offering. The first time a DC is set in this material it's the oft forgotten Nature, used to sus out something about the three suns in the sky. That's the kind of consideration for the fiction that's going to make some players happy.
I appreciate that there's a bit of a point crawl, bit of a delve, and a nice little random encounter table which isn't exactly commonplace in the 5E space. It all paints a great picture of the realm of fire and if anything I'd like to see the results of that table expanded to provide even more interesting encounters. Love that Fire Giant tug'o'war result!
Toward the end of your pages there's also a great bit of occultism with the nails and wraith that just warms my heart to see. Weird magic and esotericism is so goddamn good.
This is kind of jam packed even if it's limited by the format of the game jam. If you wanted to expand on this I think it would be really interesting to see fleshed out!
My only critical thought in terms of what's provided here is that it's not clear to me that a level 10 party would be challenged by the mechanical numbers provided. This is a pretty faint critique but it's worth saying that in 5E small amounts of damage, checks to open portcullises under no pressure, some of the DCs in general, can all probably go up a ways. Similarly I suspect that the titular Efreeti could really use some bespoke statistics, maybe even legendary status in order to provide a proper climax!
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Finally I just want to call out your art process as worthy of a bit of praise. You blended several sources really well and I'm not even really sure where some elements might be edited or not based on the intelligent use of all these assets. Tutor of the Ifrit's Art looks really damn good!